The reason Sonic couldn't go super in the first game is because there were only six Chaos Emeralds to collect instead of seven.
This one admittedly might be obvious to others, but why is the infamous port to the Game Boy Advance called Sonic the Hedgehog Genesis, when the "Genesis" part would already be implied (e.g. by the box art)? Because an identically-titled game was released the very same day.note It wasn't the best day for the franchise.
Why do Eggman's machines here seem so lackluster compared to the things he'd make later? Because Sonic just plain caught him off guard, and Eggman's scrambling (heh) to make something to fight this impossibly fast hedgehog before Sonic gets through his previously adequate robots. It isn't until the last bit of Sonic 2 that he starts making machines specifically to counter Sonic. Until his future nemesis came along, a lot of his machines could easily trump most things that tried to get in the way.
