Look at that subtle off-grey colouring, the tasteful thickness of it... What the hell happened to modern GUIs, man. We peaked in the 1990s.
I completely understand people like Andreas from SerenityOS and the idea that there was a time that was a peak of GUI simplicity yet usefulness for power users.. In their case it's the Win2K aesthetic but I think OS9 is pretty close to that level of streamlining. As amazing as OSX seemed when it was launched, I partially blame OSX and the whole "make everything round and groovy and graphical goodness" trend that star…
This reminds me: There was pretty interesting community of Linux users customizing X11 desktops in the late 90s and the very early 2000s... When the first screenshots and demos of OS X and Aqua came out, almost immediately, people tried to imitate that.