I kinda miss that in the early 2000's kde and gnome shipped with a fuck ton of window decorations based on all those (then-not-so) old OS. Teenager me had fun switching them every day and playing with windowing behavior (focus follows mouse! hover to select and only one click needed!). I wonder what techy kids today do to explore and have fun.
Speaking of the early 2000's, man, Aqua was such a good design. I appreciate the nextstep paradigm and design, but Aqua was just so futuristic, in a good way.
Yes Aqua was quite striking. Also much more consistent than the rag bag of different styling you see on Windows or Mac today.
Even before those, AfterStep, Enlightenment and many others were really nice.
In some ways X11 with it's focus follows mouse, don't raise on focus, select:middle click paste features provide a far more refined desktop experience then mac or windows ever could. No wait, stop laughing, sure X11 was a garbage fire when it came to consistent professional design, but because it was such a wild west of an environment there was place for real ui innovation. I know, I get grumpy fast without middle click paste. And I hate having to raise a window in order to click and type on it(A common access pattern for me is to read docs on the top window while I am operating the bottom window).