Contrary to general conceptions, due to relatively high wages and the proliferation of iron throughout the intervening millennia, technology ramped up again in The High Middle Ages which saw the introduction of cranks and wheelbarrows, European copies and improvements upon the mechanical clock, Arabian-style windmills, and the re-introduction of the old three-crop rotation system; the medieval world changed a fair bit in its time, not least because the population of Europe nearly returned to the level it had been in Roman times until the decades before the Black Death, which were marked by population stagnation. The aftermath of the Black death being a time of (re-)industrialisation, as the relatively high cost of wages in de-populated post-Black Death Europe gave landlords a big incentive to buy tools like shovels and hoes rather than just hiring more labourers. Even the so-called "Dark Ages", to the extent it could ever be said to exist, was just a Western European phenomenon. In the Eastern Roman Empire and Eastern Europe in general, the Arab world, the Indian subcontinent, and the Chinese realms were, though constantly in flux—with major fluctuations in population and general prosperity levels due to the wars and chaos accompanying the rise and fall of several different empires—largely as militarily and culturally sophisticated as ever, their empires having done much better to resist the encroachment of the peoples of the Steppes (Mongol-led Empire of the Yuan aside). The idea of a medieval decline is a trope in itself, which has been around since the Renaissance.
Remember that until very recently in history, Eastern Europe and the East (i.e. Asia) was wealthier, more prosperous and more stable than Western Europe. The real reason why the medieval era or the Dark Ages is even remembered as such is that it was precisely the last time the people in that land could conceive or know of such a lifestyle, and the arrival of relative progress naturally led many of the beneficiaries to castigate the earlier intervening era as a dark age. Furthermore if you compare the Medieval European era with the Ancient Roman era, the average lifestyle enjoyed would be superior to anything in antiquity. The medieval era, in Western Europe, saw the end of slavery of fellow Western Europeans and the Black Death saw the gradual end of serfdom, and it saw many nascent peasant rebellions and other agitations that led to higher wages and improvement of a kind that the Ancient Romans never provided to any of its subject peoples. Indeed, in the Roman era, the domains of Western Europe (the area of land conquered by Caesar and his successors) was so poor and backward that it was literally left to decay in the Crisis of the Third Century and the Eastern half of the Empire more or less allowed a corridor for Attila the Hun to raid it and leave it alone. To the extent the Dung Ages ever existed to start with, it began in Late Antiquity (when serfdom was first instituted).
Many forms of media focus on historical inventions because it seems logical that scientific advancement and inventions result in economic growth. As far as they are concerned, this is the story of human development—Science resulting in Modernity. Historically this has only been true over the last four hundred years or so, where we see and experience that linear organized proliferation of ideas in economic and social activity. This fact of history is why some engineers, historians, and economists alike are bemused at the idea that Archimedes alone could have started the Industrial Revolution two millennia early. The Roman Empire, the Empire of the Song and the Mughal Empire were all pretty damn big and culturally sophisticated, but their populations didn't craft precision optics or found joint-stock companies or use square-rigged sails because there was no reason for their peoples to use those things. In other words, necessity is the true mother of invention. Homo erectus adopted the technology of fire not because Prometheus told him to invent technological wonders to rival God; it's simply because fire defended humans against nocturnal predators, and also made food easier to digest, parasite-free and safer to eat, thus more families and less roundworms. Desert civilizations such as Mesopotamia and Egypt invented farming because hunting-gathering in a desert will just kill you, square-rigged sails became popular because of inter-continental trade that involved loads of down-wind sailing (using the so-called 'trade winds'). Arguably the only major (material) difference between Europe in 1500 and Europe in 1800 was the presence of the million-plus muskets. Then again, for us modern humans, inventing nature-controlling technology for the sheer pleasure of it may count as a necessity too.
Scientific progress, moreover, was very slow-paced from c.1400 to about c.1800 (even at which time the use of the so-called 'Scientific Method' was still far from universally accepted) and had no practical applications beyond navigation, time-keeping, and of course war—most European people, even in the more advanced parts of Europe like the Dutch Republic, were dirt poor and died young just like their compatriots in Colonial America, Bengal, the Sudan, Java and Guangdong. The nature of most changes that occurred in that period concerned weaponry, the deployment of weaponry, and institutions for making and using and acquiring the money to make and use weapons—it was only with the advent of the Industrial Revolution that people started becoming better-fed, living a bit longer and dying less. Indeed, it was only in 1865 that London completed its public water- and sewer-works; the first of its kind in the world, it was decried by the scientific community as a shameful example of governmental spinelessness in caving in to the demands of the so-called 'sanitarian' pseudo-scientific movement, which was making wild and unsubstantiated claims that the use of soap and general cleanliness would reduce the incidence of disease.
Continual technological progress has never been inevitable in human history, even though modern capitalism makes it feel inevitable in developed countries today, with the expectation that newer and better versions of everything will come out every year. Different societies adopt and phase out 'technologies' according to their needs for survival/pleasure/social status. Even if something's a cultural-legal tabboo, if using something better suits a society's needs (e.g. accepting the wealth of non-noble merchants, radios in North Korea) it'll be done anyway and will almost inevitably become acceptable in time. Many peoples never invented writing, ceramics, wheeled vehicles, and some not even agriculture. Cultural anthropologists and archaeologists don't have one universal answer for why this is—reasons can include lack of necessary resources (minerals, animals, plants, population, climate, energy, etc.), cultural aversion to a particular technology, or (and this is the biggest one) just plain not needing to adopt something new. Many a method and/or tool ('technology') has been abandoned when others are more profitable and/or convenient, such as the gradual abandonment of firewood in England in favour of coal note While all human cultures continually adapt the technology they already have to environmental and social changes—and thus true stasis never happens—people don't tinker with, much less adopt, entirely new technologies without significant economic, military, social, or other incentives making it a good idea for at least some of them to do so. Anthropologists are just as interested in figuring out why various technologies were invented at all, as in why some societies didn't invent or adopt them until others had a marked competitive advantage.
