Why did UI's turn from practical to form over function?
E.g. Office 2003 vs Microsoft 365
It's easy to remember where everything is with a toolbar and menu bar, which allows access to any option in one click and hold move.
Seriously? Big ribbon and massive padding wasting space, as well as the ribbon being clunky to use.
Why did this happen?
The cynical but probably truer than we'd like to admit answer is "middle managers who bring nothing to the table but need to 'make big changes' to justify that promotion they've been chasing."
Source: Pretty much all corporations at this point have these people, my sister's ex-husband is one at Google.
Change for the sake of change is so dumb. I'm tired of pointless UI changes every so many years because some middle manager and their designers need to wow some dumb exec to get a promotion and they do so just by rearranging all the existing functionality because the product itself is already a complete solution that doesn't actually need a new version. Sadly, this mentality even creeps into FOSS spaces. Canonical and Ubuntu wanting to reinvent the wheel with Unity, Mir, Snap, etc. GNOME radically changing their UI all the time.
To be fair to the Open Source community, Canonical is a private company, and so it's not really a shocker that they keep promoting bullshit tied to their own ecosystem. Especially with someone like Mark Shuttleworth involved, he was one of the early rich out of touch space tourists, long before Bezos looked like an idiot coming back from space. The profit motive always infects everything it touches.