Metro was also just pretty bad on its own, irrespective of what came before or after. It was way too simplified, and despite that everything was HUGE so you could really see every bit of detail that was taken away. As usual, Microsoft was chasing the big new thing that never came by designing half the OS around tablet PCs. Windows 10 toned it down like how 7 toned down on Vista, and after that it was pretty alright for me. A much better example of a UI that came out then and aged well was Android 5 with Material Design.
This was a late 90s/early 2000s thing. I remember it on some Win98 and XP applications.
[0] https://i.redd.it/9fhcm9ce0ao21.jpg
[1] https://klanghelm.com/assets/img/VUMT/VUMT-2-solo-full.jpg
Gen Z like it because of nostalgia, not because of quality or because it actually looks any good.
https://en.wikipedia.org/wiki/File:Plasma_Workspaces.png - ugh.
It was especially confusing at the time because Windows XP was so straightforward and correct. Flat, contrast-heavy UI elements that overlap without interacting when they aren't supposed to. Drop shadows used for good instead of evil. Skeumorphic design elements that are intuitive, not desperate and corny. The cutting edge in PC usability is arguably still technology designed in 2003.