I agree about the excessive eye candy in X. I'd love to run a stable OS 9, keeping the sane finder, the proper font rendering, a professionally-chosen mouse response curve and the blazing UI speed!
But at the same time, I have to admit X is doing things 9 couldn't dream of without a serious under-the-hood rewrite. OS 9 was limited to 2GB files IIRC. I download and burn 4GB - 8GB DVDs in OS X quite regularly. The 31-character filename limit wasn't a huge hinderance, but every once in a while you want to name a file "Resume 050731 as sent to Jamie Blanco at HugeCorp for the EE position", and it's nice to be able to do that.
If people remember, true "video on your computer" was still a pipe dream in the late 90s. (I'm referring to storing movies on your hard drive, watching them, editing them, and outputting them.) Now I can download shows on my cable modem then transcode videos to true DVD. On my dual G5 it's just drag, click, let it run for an hour. iChat does four-way video conferencing with ease, at least that's what I hear.
Incidentally, I had the pleasure of booting up a Mac Plus at work today. It was fun. Yes, the mouse was amazingly responsive. But I started noticing a lot of things...missing. No real multitasking - heck, no multifinder! Only one application open at a time, please. The finder was so slow you could actually watch windows redraw. (Kind of like X on an older G4..) The art on the tiny black-and-white screen looked pretty nice in a retro sort of way, but any off-the-hand snapshot with a digital camera blows it away.
Sure, if all you do is write papers and send text email, you could still live on a 1980s computer. You could even make a living. But modern machines let you do entirely different types of things than you could back then. I miss the old ways sometimes, but I wouldn't go back.