Because it's not Linux and certainly because it's not Windbloat. My primary OS is Linux with XP hanging around mostly for my game (DAoC). I like having a clean and snappy OS to escape from X11 and XP.
The one thing I do feel wealthy in this, is the community. I feel apart of it, I know even as a none coding or none artistic individual, I can make a slight difference. The same would be pretty hard to be said with a straight facee in regards to *nix or Windows developer enviroment.
Dammy