I understand not every decade was a clean break, but each decade has fairly distinct defining properties. It feels like most of the 21st century has been a single run on with smaller changes. I know sometimes the definitions don’t come into focus until later, but I’ve been around since the 80s and I can distinctly remember the changes between the 80s, 90s and 00s as they were happening.
20th century saw huge technological change - maybe the greatest of any century - and constant pressure for music and marketing to evolve year upon year. Society was fractured following the fall of the old empires and this allowed people to embrace new political and lifestyle ideologies - everyone was literally becoming more liberated with every passing decade.
In contrast, we’ve been at a bit of a technological plateu since the turn of the 21st cen. (I say blame the lobbyists from oil and gas, but I digress). Marketing and music nowadays is under pressure to conform rather than innovate, so styles are more likely to draw upon their antecedents and contempories than experiment with something new.
You could also interpret it as: after much experimentation, society has settled on a set number of fashion styles and musical styles we all really enjoy - and it’s anchored around the 1980s, which is why thing keep on “looking back on” 80s culture with nostalgia. The things that do change nowadays are digital art styles, AI slop style, and web interface. Somethings just “plateau” for a while - technology in the dark ages, population prior to the industrial revolution, and fashion, from around 400AD to 1500AD.
And one last element - in america, the 20th century saw continuous development of economic well-being, on average, as more and more oil and foreign countries were exploited. This allows people to be creative, and the visible rapid change of society represents the visible flaunting of its’ citizens’ wealth.
The same would not be true for the Soviet Union, for instance; for although it saw major economic stabilisation, communist russia didn’t see a very rapid progression in family wealth, and you can SEE that they have very similar art styles and architecture from the dawn of the century right through to the end - no flaunting of wealth.
Even countries like Britain didn’t get noticably richer from 1945 to 1991 and I’d argue you can definitely see this in our cities, where we’ve been afraid to knock down old buildings where america wouldn’t hesitate. Britain did see dramatic changes in style, in-line with america, but this is expected because it’s a satellite state of the American “empire.” See, our styles and architecture since 1945 have largely not been our own, that is how strongly influenced we are by the big dog USA.
Would also love to hear your own thoughts on the matter, u/[email protected], I’m sure you have your own theories