Both Apple and Microsoft had interface guidelines documentation for years and while Cupertino was able to kept their software pretty much unified visually through the years, Redmond was and still is less consistent in applying such rules [1]. In period between Vista and 7 there was a really dedicated community (Aero and later Windows Taskforce) who tried to give Microsoft hints where polish the Windows environment only to see their efforts being largely disposed with Metro introduction.

Apple had to pursue the literal new shiny thing because their AI endeavors backfired - it's all a distraction which also didn't work as they expected. In the all of critical comments I liked one that replied to me here on HN, where user compared Liquid Glass to pouring a corn syrup over the interface.

Operating systems for mainstream users are mostly complete so companies have to focus on visual aspects of their products much more. This is obviously nothing new but watching that WWDC25 I was really amused how these people were disconnected from real world, how marketing side has dominated usability of Apple products. For me that was the actual reality distortion field in use.

Bulky, rounded interface become popular shortly after flat style become dominant in our digital life. Liquid Glass is really close to Gnome's Adwaita, Microsoft also tends to follow similar style. I can't bring the source but it was pointed out that rounded interface and graphics overall are giving some level of comfort, a sense of "safety" unlike than anything sharp and "spiky". This seems to be related to the bouba-kiki [2] effect.

[1] - https://full.pr0gramm.com/2024/08/23/7c0cbd6101844c44.png [2] - https://en.wikipedia.org/wiki/Bouba/kiki_effect?useskin=vect...