There is definitely an element of nostalgia. However, a lot of earlier desktop OS GUIs do seem to be more internally consistent and with more emphasis on usability than the current crop. I think part of the issue is that things that might make sense on a phone have bled into desktop OSes, where they make a lot less sense.
I don't mean this in a dismissive way but based on your profile I'd say you're > 25. I'm curious about the perspective of someone who didn't grow up with the those os's
You’ll need an under-25 who’s both used some of these enough to really understand them, and has watched others of mixed expertise levels use them, to get a meaningful opinion. Screenshots don’t cut it, for the same reason as why modern UIs can look slick in screenshots or a demo then be frustrating in actual use.
That person’s gonna be very rare, while lots of over-25s have that experience.
25 is a very distant memory. ;0)
I’m > 25, but I didn’t use those OS. I started with Windows XP, then did a bit of playing around with Gnome 2 on Linux Mint. You wouldn’t call them pretty, But you never had to guess about an icon or if an interaction was possible. It was pure get things done (barring crashes and slow hdds).
Today’s OS are aesthetically pleasing, especially with the right combination of windows, but using them is a frustrating experience.