I think it's got more value as a status indicator. You can use the sounds to determine what's going on... from several doors down the hallway.
Thinkpads make a unique sound when they come on and off an external power supply. You hear a bunch of these in conference rooms just before and after a meeting.
XP and 2K default startup sounds are different so you can tell them apart... but they're still user-customizable.
This is just one more example (as if we need any more) of Microsoft taking choices away from their customers.