From Mists of Pandaria, the Pandaren starting questline introduces two NPC's who become the racial leaders for the Alliance and Horde factions of Pandaren: Aysa Cloudsinger and Ji Firepaw. They take complete opposite approaches to life and most situations, with Aysa being reflective but slow to act, while Ji is decisive but brash. The two are supposed to be equals with their own strengths and faults, but throughout the questline, Aysa comes off as much more elegant and professional, while Ji is a hotheaded oaf who runs headfirst into everything, invoking Women Are Wiser. He's also constantly praising her beauty and finding time to flirt even though their island home is dying. It isn't until the end of the questline that Aysa is shown in a negative light by stubbornly refusing to admit Ji's ability to think on his feet saved the day.
Before and during the events of Cataclysm, the dwarven General Twinbraid was portrayed as a Sociopathic Soldier who built a dwarven fortress on tauren lands to research a Titan complex and justified his actions because of extreme Fantastic Racism. When his son died in a flying machine crash caused by the destruction of his fortress, itself built upon stolen land at the expense of the tauren, Twinbraid opted to deal with his grief by attacking and killing innocent Bilgewater goblins solely out of his own hatred, admitting he would have done it even if there was no strategic value. This Hate Sink characterization apparently was not passed on to the writers of Mists of Pandaria, as there Twinbraid, now promoted to High Marshal, was re-characterized as a more sympathetic character, trying to stop the Horde to prevent other parents from suffering the loss of a child like he did, which not only doesn't gel with his existing personality but comes off as a complete abstaining of responsibility from his actions and those of his son which caused it in the first place.
Malfurion Stormrage, despite being billed as an Alliance hero and a great, wise leader, is disliked by many night elf fans due to his apparent disinterest in actually supporting the night elves against the Horde. He doesn't lift a finger against the Horde in Cataclysm, despite the orcs rampaging through Ashenvale and killing his people, and due to how he was programmed, he wouldn't even step in to protect his wife Tyrande if Horde players attacked her in Darnassus despite lore portraying them as a loving Battle Couple. Patch 4.2 decided to address this somewhat by showing that the previous Archdruid Fandral Staghelm was anti-Horde to protect his daughter-in-law and granddaughter, and that Malfurion's inaction got said granddaughter killed. Leyara, Fandral's daughter-in-law, raged against him for this. Battle for Azeroth would eventually take steps to correct this by showing Malfurion as Neutral No Longer and fully willing to fight back against the Horde for their invasions.
Horde-side, Baine is intended to be the "Heart of the Horde" and Only Sane Man, viewing naked aggression as a horrible thing, and is supposed to be the voice of reason. Unfortunately, being the voice of reason and advocating non-violence translated into justifying an Alliance firebombing of Camp Taurajo, banishing his subjects who wanted to fight back against the Alliance forces invading their land (whom were led by people like General Twinbraid, mentioned above), and generally acting like the Alliance is in the right to want to 'punish' every single member of the Horde, even when the Alliance is clearly the aggressor. The tauren in the camp, he exiled, Vendetta point, also came across as sympathetic and literally stopped an Alliance force from invading the Tauren capital during quests, making Baine come across as an Ungrateful Bastard. It got even worse in Battle For Azeroth, where he openly advocates surrendering to the Alliance at the funeral of a king the Alliance killed in his own city, right in front of his grieving daughter. All in all, Baine can come across more as a war hawk, only in favor of the Alliance rather than his own faction.
In Legion, Aethas Sunreaver rejoins Dalaran by trading information on Felo'melorn (the royal blade of the Sunstrider family) to the Kirin Tor. This is presented as his personal quest for redemption, but a lot of players interpreted it as an act of prideless grovelling that only cemented his status as The Scrappy. The notion that Aethas would use his race's most prized artifact as little more than a bargaining chip is often criticized as disrespectful; blood elf fans in particular tend to express outrage when the subject comes up. Aethas then goes on, rather tritely, to have his faction compromised by traitors again, and although he handles it better this time, it's done nothing to dispel the many accusations of incompetence hurled his way by fans. That Aethas gets considerably more screentime than his far more well-liked counterpart, Rommath, also contributes to this.
While the death of Kil'jaeden halfway through Legion is portrayed as an Alas, Poor Villain moment, the sheer amount of suffering he has caused throughout the Warcraft universe: helping destroy his own planet, tricking the orcs into going into a genocidal war with the surviving draenei (and later, races of Azeroth), creating the Lich King (and by extension the Scourge and Forsaken), trying to corrupt the Sunwell, etc., it seems a lot more like a case of Karma Houdini Warranty expiring than a sad event, especially since it's certainly not a case of Redemption Equals Death (indeed, he doesn't even apologize for anything he's done).
Thalyssra and the Nightborne was hit with this hard during Battle for Azeroth. They joined the Horde even after the Night Elves came to her aid during the rebellion, because of Tyrande's dismissive attitude and because they want to join the world "as protectors, not conquerors". The problem is that most of Tyrande's grievance towards them are completely reasonable, as well as the fact the she still went out of her way to aid Thalyssra's rebellion. The fact that the Nightborne willingly go through with burning down Teldrassil, killing hundreds and thousands of Night Elf civilians in Battle for Azeroth made Tyrande's concern came across as completely founded while making Thalyssra came off as a massive hypocritical Ungrateful Bastard and the Nightborne came across as expecting the Night Elves to fawn over their footsteps after thousand of years hiding away and then allying with Burning Legion.
The Horde in general and the orcs in particular are victims of an increasing perception among players that they are evil or at least villainous. Blizzard themselves codified the idea of orcs and monstrous races not being evil in Warcraft III, instead showing them as unwitting pawns under the influence of behavior-altering magic from the true villains, and as cast-out underdogs in a world that hates them. As World of Warcraft's expansions went on however, orcs and the Horde increasingly antagonize the Alliance with little provocation or reprisal for it. This culminated in Warlords of Draenor, which showed that the orcs would have still become genocidal warmongers even with less manipulation required from demons, and Battle for Azeroth, which sees all of the Horde (and several previously honorable characters) jump headfirst into a war of extermination against the Alliance for no real reason. And when they do start to rebel against Sylvanas, it's because her growing paranoïa means that they now are at risk as well, instead of out of any moral reason. Thus they have begun to come off less like dark heroes unfairly persecuted for past crimes, and more like they are rightly being persecuted for crimes they keep committing. And when Sylvanas stops being Warchief, it is not out of any moral concerns, or fears that they were going too far, but because Sylvanas tells the Horde that they are worthless to her. Obviously this trend has become controversial among those Horde fans who liked not necessarily being the bad guy.
Saurfang himself was hit with this as Battle for Azeroth went on. Saurfang is intended to be someone who realizes he's been tricked by Sylvanas, sees the Horde going down a dark path, and is at a loss of how to fix it, ultimately killing himself dueling Sylvanas so the Horde can see she does not care about them, only herself. The ones still loyal to Sylvanas see Saurfang as someone who cares more about the Alliance than about his own faction. The ones who hate Sylvanas would like Saurfang, but it's at least the fourth genocide he's "accidentally" a part of in fewer than forty years. Also, Saurfang is the strategic mastermind behind the War of Thorns, accepting to lead and plan it on a very flimsy reason ("the Alliance might attack us in fifty or a hundred years, so let's cripple them for good before they can be a threat"). He led the Horde through Night Elven lands, personally killed Night Elves, and agreed with the idea until he suddenly had a crisis of conscience in the last five minutes of the war. Then, rather than try to fix the Horde from within, or challenge Sylvanas for leadership, his first reaction was to deliberately get himself killed in battle, making it feel like he expected others to fix the mess he helped create. As such, Saurfang blaming Sylvanas for "what she did to the Horde/Teldrassil" feels like a disgusting case of Never My Fault, making Saurfang avoid any kind of responsibility for his participation in it. Even if you still wanted to sympathize with Saurfang, there's the glaring fact that, despite the entire War of Thorns being explicitly called a genocide of the Night Elves, most of the expansion's story was about how sad it made Saurfang to be complicit in genocide again, to the point of giving him multiple high-quality full CGI cinematics about it, rather than about the actual victims of it. Even Saurfang's death and the leadup to it, which shows him confessing that the Horde has been rotten and evil for longer than he wanted to admit, does little to alleviate the above, since he still got the warrior's death he wanted. Saurfang is presented as heroic throughout, still doesn't answer for his crimes, and still hogs the spotlight from the actual victims of the genocide he was partly responsible for. All in all, despite Saurfang being portrayed as an honorable hero, it's pretty hard to sympathize with his plight when he's knowingly made the world a much worse place.
Anduin Wrynn, was hit very hard with this trope as Battle for Azeroth went on, due to solely focusing on removing Sylvanas (believing her to be the sole reason the Horde is bad again) when various quests and stories in the lead-up and during the expansion made it clear that a majority of the Horde supported and happily participated in what Sylvanas was doing. Then there's the fact that his treatment of Saurfang (see above for more on him) is entirely too lenient considering what Saurfang did, and a majority of Anduin's screentime during the expansion is either about trying to spare Horde lives (refusing to press the advantage after the victory at Dazar'alor and ending the war quickly in favor of the Alliance), insisting that the Horde can still be good (most egregiously, he offers a "both sides" rebuttal to Saurfang admitting that the Horde was evil from its inception, despite the list of Alliance atrocities being ridiculously shorter than the list of Horde ones, and at least one of those criminals arguably had his beliefs vindicated by the Horde's actions throughout the expansion) and his only scene with Tyrande had him calling her (very, very justified) desire of vengeance as her being unreasonable. All in all, it's no surprise many players outright call him a traitor to the Alliance he's supposed to lead.
Battle for Azeroth adds another one: During the faction Assault in Vol'dun, the 7th Legion learns that the local vulpera are transporting war supplies for the Horde. The commanding officer strictly tells the adventurer not to kill the vulpera, as they have no quarrel with them and only want to dissuade the vulpera from helping the Horde. Instead, the adventurer frightens the vulpera away from their wagons and destroys the supplies. This all seems fine and dandy, but the rest of the 7th Legion in the area are killing the vulpera outright and burning their wagons (which are their homes). Considering that the player is sending the vulpera into a panic, fleeing heedlessly into the desert, next to a major sethrak camp (the vulpera's enemies), it's unlikely all the fleeing vulpera will make it out of the area alive. The vulpera themselves see this as bullying behavior at best, as it means the Alliance denies them an honest livelihood and well-paying jobs. The Alliance seems less heroic and more completely focused on the Horde's destruction, regardless of civilian casualties.
Jaina Proudmoore in war hawk approach came off as this, as despite the bombing of Theramore being treated as a horrible act against an entirely innocent city, Theramore had often given assistance to the Alliance or made hostile actions towards the Horde, meaning that Jaina's anger, while understandable, didn't feel entirely justified. The problem only continued when the writers inconsistently wrote Jaina to be more war hungry or less in the following expansions, which made some feel that Jaina no longer was sympathetic to how inconsistent her beliefs and actions were.
Elune herself was hit by this in the Ardenweald finale. The explanations as to why she didn't help more at the Burning of Teldrassil (she did all she could, but couldn't prevent it from happening), the fate of the Night Elves' souls (she tried sending them to Ardenweald, but the Arbiter being dead instead sent them all straight to the Maw, and due to being a goddess of Life, she didn't know what happened to the souls, nor could she intervene to help them even if she did) and her saving Tyrande (directly intervening to save her life from the overwhelming power of the Night Warrior and then giving her the chance to move away from a blind vengeance that was literally killing her), intended to present her as good but limited in what she could do instead came across as her being extremely dumb (she knew enough to be aware there was something wrong within the Shadowlands, but didn't bother checking what before sending thousands of Night Elven souls there), incompetent (the only help she provided during the War of the Thorns was making the night elves die painlessly and preventing Saurfang from killing Malfurion, and she simply tried to send the night elves' souls to the place they'd have gone to anyways, while all the lore about her prior to Shadowlands implied she was capable of more than that, such as awakening forest spirits and the likes) and manipulative (Tyrande became the Night Warrior fully knowing and accepting it would eventually kill her, and yet Elune had already temporarily removed her powers when she was seconds away from killing Sylvanas, making it look like Elune was willing to let Tyrande choose between vengeance or renouncing it, but would keep asking until Tyrande chose to give up on it, nevermind that Tyrande's "blind vengeance" was seen as entirely justified by players, or why Tyrande couldn't have both vengeance and renewal for her people.). Making Elune's appearance and explanations received even worse was fan-favourite Bwonsamdi, implied to be much lower than her on the cosmic totem pole, outdoing her on all three (he raised the dead and directly empowered Rastakhan to help defend Dazar'alor from the Alliance, went out of his way to prevent troll souls from going to the Maw, and for all his entertainingly dickish dialogue, was straight-forward when it came to help the Shadowlands). While the latter two at least have the justification that Bwonsamdi is a being of the Shadowlands and as such is in a better position to help, it still makes Elune compare unfavorably, and she has no excuse for the first.
Taelia Fordragon being upset at her father for keeping his survival as the Lich King hidden from her. While it's understandable that she is going through a lot after learning that her father isn't dead as she thought, she acts as if Bolvar selfishly abandoned her and displays little sympathy for the torments and sacrifices he endured to keep her and Azeroth safe.
The Forsaken race from its very inception has flip-flopped between this and Hate Sink, Depending on the Writer. On the one hand, their Freudian Excuse is that they were slaughtered by their beloved prince, enslaved in undeath to kill others (including their loved ones), and when they were finally freed were rejected by the still-living humans. On the other, they almost constantly commit acts that cross the Moral Event Horizon, such as plotting the death of all the living - including their ostensible allies the Horde -, lobotomizing and enslaving living humans like Theresa, and destroying the environment. For many fans - typically those of the Alliance - the lack of sympathy comes from the lack of acknowledgment of the Forsakens' evil deeds, as well as their focusing of their deeds almost exclusively on the Alliance. In addition, the writers rarely try to portray the Forsaken as being worthy of sympathy, but often still act like they are a decent faction, and every time they have a sympathetic Forsaken character, they tend to be killed off, instead having characters say the Forsaken deserve it.
