I am a Millennial and I don't give a crap about fashion and trends. I want something that
I like and is good to use. I found some old UI's ugly and clunky. I find the trend of material design just that: a trend. Just like Baroque, Rococo and Renaissance were trends. Which eventually faded, like all trends. Just like Material Design will fade. Some young people are rebels just for the sake of rebelling, and therefore it
has to change regardless of whether the change is good or not. Cool, though sad. Those are the ones that most likely will become conservatives later on, as they're just following emotions. Some older people are conservative because "the good ole times when everything was better." I fit in neither, which is kind of lonely but it is what it is.
I love the W11 design, best looking one so far. Usability is not bad. W7's was better in some regards, worse in others.
I hated W10 design. Usability was poor.
W7 design was nice. Usability was good.
Windows XP design was ugly. Usability was nice.
Windows 98 was ugly. Usability was ok for the time.
The others in between are not worth mentioning.