I'm a bit too old to have been privvy to any Win XP design backlash, but I think the more apt comparison is with Windows Vista, where transparency was also a major part of the design philosophy (usability be damned). We have pretty good ideas about what makes a good UI/UX and none of those ideas involve using transparency to make readability worse while also not really making what's under the half-transparent element visible or readable.
1. There's actual value in getting used to things. Part of the reason older people can't use computers well and get scammed is because trendy software companies constantly reshuffle the same stuff and they can't keep up.
2. A lot of UI progression is objectively worse, and I do mean objectively. Less legibility, more clicks to do the same actions, etc. We just get used to back software.
iOS 26 is bad software. We might get used to it being bad one day. It's still bad.
Similarly, Windows 8 was bad software. We actually undid that one.
For example, many websites optimize for engagment and in the processes make their website WORSE. Because people have high engagement with shitty things. Thats why humans can't look away from a car wreck.
UX designers are basically creating car wrecks so they can say "look at how many people are looking at us!"
Yeah, I wouldn't brag about that.
Windows 8 was bad software for desktop and laptop computers. I will say though that it was great for hybrid tablet computers and they should have kept that interface for them. Using a Surface running Windows 8 is much nicer as a tablet than what Microsoft has done since. I have no idea why they thought a tablet interface was a good idea for desktops though.
Some Microsoft VP saw an iPad and said 'That! Do that!', and the dominoes just fell from there.
The first rule of UI design is don't change things. The second rule is to make it easy to revert exactly to the prior layout. For webpages and apps, it's not hard. Don't change things. Do not change things. Do. Not. Change. Things. But UI designers are too stupid to grasp the simple rules.