The reason why things were more varied in previous generations is the speed of communications. it took much longer for fashions to permeate through society, this mean that more local variations happened.
Now, fashions are almost always global, but they still change at the same rate. The difference being is that they change much more in unison across the globe.
(I've been observing this for at least the past 15 years or so. This feels more like the "post-history" of fashion.)
Edit: Regarding the speed of communications, mind that there were much read, trend-setting magazines, which came out periodically, every week or every month and that they had to make a point, relative to the previous issues. And, as a reader, you wouldn't have referred to a past issue from half a year ago. Moreover, past issues were hard to come upon, as they weren't sold anymore. Now compare this to websites, which keep lingering around (you wouldn't discard last month's posts) and platforms, where trends gradually gain momentum, until they eventually become ubiquitous. (At this point, a trend would have been "out" and "uncool", previously, but now this is when they are really enforced by algorithms.) I'd rather argue, for things like fashion, the speed of communications has decreased considerably and stability has increased, thanks to technology.
E.g., https://www.washingtonpost.com/home/2022/10/27/why-victorian...
The idea was the world went through a drastic change with WWII and the Victorian mansion started seeming like a ghostly remnant of the earlier age.
Antiques Roadshow had a similar podcast where they discussed the "brown is down" phenomenon.
Did the fast-changing fashions of the postwar era reflect something about normal trends, or was it a sort of equilibrating phenomenon, and now we've returned to some normal again, that we haven't seen in over 100 years?
I wonder if you were to travel pre-world-war era if you'd come to the same conclusion about the speed at which fashions change. Maybe but maybe not.
Coincidentally I was talking to my spouse last night about how if you look through architecture and design websites and magazines, the stuff you see is different from what we were referring to "real estate style" and here was referred to as "Airbnb" style. In architecture and design circles there's less uniformity and more color and contrast.
The problem with this I've found is that it's difficult to find something different, of the sort in architectural circles. So if you want some of this stuff you often have to have it custom made, or made by a single boutique manufacturer, which is expensive and difficult.
So some of this uniformity in style I think is international economies of scale, which creates supply constraints and a sort of monopsony of sorts. This might be reinforcing in turn.
I don't know why the English-speaking cultures are so quick into reducing it into "Victorian", but it was recognized as a time of quick change.
I'm living in a city where most of the buildings are 100+ years old. (The house I'm living in was built in 1904.) You can usually date a building from that era by about +/- 2 years of accuracy, just by the looks, regardless, whether it's art nouveau or a more conservative expression of style. However, as you approach WWII, things considerably slowed down. (Mostly for economic reasons.)
I think, this idea of a mostly stable era is a product of the shift in paradigms, you mentioned before, where we put anything that happened before in a paradigmatic box. (E.g., like it has just recently happened with brutalism, where a wide variety and evolution of concepts and oppositions was subsumed into the same thing.)
It feel like we're stuck in a global, homogenized, test-group-approved fashion loop.
Of course cars are going to look mostly the same. If you change anything too much (e.g. cybertruck) you're just straying from a highly optimised design.
Look at bicycles. Before the invention of the safety bike there were lots of different designs. But the safety bike is such a good design you can't really get away with it.
Or phones. Everyone complains about glass rectangles and where are the sliders and flip phones? They don't exist anymore because the glass rectangle is such a good design.
Who cares if movie posters and book titles are converging towards something that markets well? The parts that matter (the content, themes, style, etc) are probably very different among all those books/movies.
IMO Fashion like this exists just so that salesmen can convince consumers that they can buy The Current Thing and earn respect from their peers. Chasing the latest furniture, latest clothes, latest cars, etc.. It's all a shallow, costly signal of wealth that excludes the not-wealthy and distracts the wealthy from more fulfilling/productive pursuits.
If this trend means that fashion is dying, good riddance.
E.g., just compare major fashion trends in the 1970s (from mini to maxi, to bell-bottoms, to pants and tube socks & disco attire, to clogs and para jackets, to college look vs. punk) to the major fashion trends of the last decade (slim fit). This variation from season to season, while, of course, invented as a vehicle for marketing, actually provided a vehicle for repositioning in a varying landscape of tribal subcultures that was typical, then.
Places like Stanford and MIT slowly become more Harvard every year IMO, and it sucks for student life too. Driving forces may not be exactly the same, but I think there are cultural undertones pervasive across these changes and some of the more superficial ones. It reminded me of this article: https://johnhcochrane.blogspot.com/2022/12/stanford-hates-fu...
Anecdotally, I think it affects science too. Grants become increasingly formulaic, and anything deviating even slightly intellectually only has a chance as a token "high risk" project. People are afraid of saying something wrong that also clashes with current scientific norms, so everything seems so damn homogenous despite the many questions we still have little answer for.
I think the "optimization" process that got us here is bad in part because it is optimizing for a single institution style that independently will do fine, and is thus a safe play for any decent university. However that is not the same as the set of institutions that would collectively do the best, not even close IMO. Homogenization can be efficient and should happen to some degree within an institution. But between institution diversity is already bad and continuing to die off year over year.
This is alarming to me and I think there is something to the aesthetics that go with it. People's behavior can absolutely be impacted by the broader cultural vibe that pervades. Signaling is important too - when you go to visit MIT and see the dingy af student center it is part of the model you build about what the school cares about. Selecting a specific type of student body is much easier when it goes both ways, because good luck assessing someone's motivations on a modern college app. When surface-level marketing becomes homogenous across the board it is going to have downstream impacts.
This has only been true for a few decades. It's a very new and foreign thing!