Honestly? I'm sick of backwards compatibility. It only works so well. There's a limit.
Especially in this day and age of virtualization.
If I want to run DOS software, I open up dosbox. Even on windows.
Why? Well, NT's VDM emulates a soundblaster really poorly. It handles resolution switches like a two legged dog.
If I want to run Win95 software that didn't have proper NT compatibilty; I launch Virtualbox or VMware with win98se.
If it doesn't work in wine, VB or VMWare to the rescue.
"Backwards Compatibility" as a meme is dead, or at least enough of a fib these days to where even game consoles cannot get it right. (PS3 drops PSX and PS2 support, 360 can only play ~150 XBox titles)
Why should you expect a PC to get it right?
Well, more to the point, why should you expect a PC to get it right when you mix several *generations* of software on the same GUI desktop?
Okay, sure, your processor can always drop back to 32bit protected mode and run freedos on bare metal, or you can still install Windows 98 (if you can find hardware drivers) or a laundry list of everything else; but it's a horrible bitch to get all of those apps open, in a window, on the same desktop.
I've tried to do this on my windows 7 professional box (gotta run visual studio 2010 for work somewhere... Even when we use QT. *sigh*)
My ubuntu box? Hey, no problem. I can goof off playing System Shock for DOS in a window while an old VB app does OLE against excel 95 in wine, with Eclipse and Chromium 12 sitting behind them, I don't have to worry about drivers (except this damned eGalax touchscreen!), and I have not *HAD* to open a terminal window in a very very long while.
Thanks to lennart, I can also plug my USB headphones in when my boss runs his mouth and poof, silence in the office.
Also, if I'm not mistaken, wasn't ConsoleKit pretty much built to bring multiuser switching to Fedora 7? I remember everyone kvetching about having to support it when it was introduced; and somehow in those years in between, it's become incumbent to the point where people are moaning about it's loss. What's next, people complaining that PulseAudio works too well?