Who'd-a thunk it???
There's another side to the UAC that I didn't see mentioned. It is actually Microsoft's get-out-of-jail-free card. You see, the UAC was purposely designed to annoy (as has been admitted). Most users will eventually turn the damn thing off so it will stop annoying them. The next week, the user gets a virus that the UAC might have warned the user about. Now, Microsoft can point to the fact that the user had turned the UAC off and say "not our problem... user error".
We Have A Winner! Yep, you got it.