Here are some reasons I had to do the past week that I don't consider "desperately need access to". MacTheRipper couldn't rip Open Season, DVDFab Decrypter was able to. Company email via web is more feature rich under Windows. The Squaw Valley ubercam looks better under Windows than Mac. It was very nice to be able to boot to Windows.
I think the answer depends on the person. Some people will upgrade immediately because of a must have feature they must have. Some people will not upgrade because there is nothing they want in the new OS. I didn't upgrade to OS 10.4 until I got a new computer because I didn't have a need for widgets or the 10.4 search feature.
When people say "stock plummets", I think people forget the 10 points or so the stock increased just prior to the quarterly results. The stock really didn't plummet, it just increased a little less than it really should have.
The iPod works with the PC and is USB only, no more firewire. Appletv works with the PC. iTunes works on the PC. The marketshare numbers just isn't that important anymore, especially sice the Intel Macs run Windows via Parallels or boot camp.
It's cool if your movies are already on iTunes. Not so cool if your movies are on DVD's (say Netflix), unless you want to do some conversion thing and some other stuff to get the movie onto iTunes.
It would be great if there was a comparision between download experience and quality between AppleTV and the Xbox 360.