I think the problem here is if people were happy with what they had in 2003, why change it?
Not everything UI-wise in 7 or later is better than in XP I'd say. And apparently many people agree.
Actually I am still using 7 and all the UI stuff that's nixer than XP or even 2000 is just eyecandy and nothing "I would totally never go back". Because I would - if I needed a stable Windows that only came with XP's UI - so be it.
FWIW, I noticed recently that I've been using xmonad for 5 years (+/- 2 weeks) and still 100% happy. It lets me work efficiently and nothing has changed.
If people were happy with Windows XP in 2003, why change it and install Linux? We deviated from what was good enough 15 years ago! Let's put XP back on the clients and Solaris back on the servers! /s
When I started using Linux, it was about thinking out of the box and about change. It had many exciting window managers that put everything in Windows to shame when it came to customizing and style.
Nowadays I have the feeling, Linux has become the resort of the grumpy and disenfranchized, clutching to whatever was cool when they were young. The levelheaded and progressive jumped ship to OSX and are now probably contemplating switching to Windows 10 after Apple dropped the ball for them. This leaves all Linux progress like Gnome and Systemd maintained by inept pompous hipsters.
If XP was secure, performant on modern hardware, stable and supported by new programs i would still be using it. More then that the reason i quit windows98 was that warcraft 3 doesn't work on it. Windows 7 configuration menus are god awful and windows10 ones are far worse then that.
You are making a fallacy in saying that old equals bad/ugly. XFCE is keeping it oldschool and can still look amazing (xubuntu looks great IMO).
There's much to talk about when talking about GUI things. Much indeed. Many things are even quantifiable, instead of being pure personal preference. Just remember that Microsoft spent a lot of effort into studies in what culminated to be windows95, while many other projects did not (the study that ended up being gnome3 is a joke in comparison).
Honestly gnome shell is the greatest thing ever. My focus and productivity skyrocketet. I see how people who would prefer to run XP dont like it. But no reason to make it bad.
Xfce, kde (possibly unity, maybe enlightenment) can do the former. Dmenu (probably unity, kde, other standalone programs) and enlightenment can do the latter (Enlightenments Everything launcher is amazing).
There are actually issues with Windows XP, the only thing is that IMO people learned how to work around those issues.
I think UIs should either change very gradually and only in ways that literally are better, but also have a way of ensuring the options aren't removed entirely, or at the very least if the option is obscure ala options removed in Gnome 2, then they should be kept and allow someone to create a tweaking tool to change them.
If a huge change is to be made, like the Gnome Shell, then it should be done in a development release and ALL of the compatible UI should be kept on the desktop, with an easy UI option to switch between the modes. It turns out that Gnome Shell could do this - but only after a time.
UX and UIs are one of those things you really should be incredibly careful about foisting on anyone. If you do it, you need to do it somewhat gently.
I'm not sure about the feature you talk about, but maybe have a look at accessibility settings of MacOS. They putted a lot of advanced settings in there targeted at various kind of handicap. However these feature can also be used to improve productivity.
Some developers even uses accessibility interface to add custom overlays & controls (Steam for instance).
> people were happy with what they had in 2003, why change it?
Because the people who were willing to run a Linux desktop in 2003 are not in any way a representative sample of the population. That's like saying "if assembly was good enough for the first batch of programmers, why would we need higher level languages?"
FWIW, I noticed recently that I've been using xmonad for 5 years (+/- 2 weeks) and still 100% happy. It lets me work efficiently and nothing has changed.