Things that are missing from today's computer desktops:
1. Multi-touch monitors. Not that you would use them all the time, but why the hell do we only put touch screens on mobiles?
2. Tabbed desktops. Just about every program has tabs for different contexts or documents these days. It's time the desktop environment caught up.
3. Zoomable desktops. MS Office has started to go the right way with a zoom slider in the bottom right corner. Desktop environments need to play catch-up again.
4. Universal file tagging, with accompanying search and browse functions. My files don't fit in single folders and if they did, I'd forget where I put them. I should be able to use ad-hoc tags to identify my files, and don't forget the ability to list all untagged files either.
Mokalus of Borg
PS - We seem to have had basically the same visual environment since the original Macintosh.
PPS - Or only slight improvements.