In California, probably because the Highway Patrol is paid off by Detroit, they require 4WD or chains in winter on many roads in the Sierra-Nevada. As you might imagine, if one goes skiing a lot, it's much easier to buy a 4WD vehicle than it is to put chains on every time you ski.
I agree, I don't need a 4WD, but it's a lot more convenient to have one. Furthermore, Subaru is the safest line of cars, and they're all AWD.