The problem is how people define skill. Being able to play your class well surely matters, but naxx especially is about doing that under specific conditions and in conjuction with a group that can do the same.
Hell, in some fights it doesn't even matter that much how well you play your class, but wether or not you can handle the conditions. Heigan being the prime example. If you fail the dance you will die no matter how well you're geared (at least in the current state for non-tanks). If you don't, you pretty much already succeeded on your part.
I'll disagree with you there. Gear is certainly important in WoW and rightfully so, but it's not everything. And the other MMOs don't fail because they are attempting to mix up the gameplay, it's because they can't reach the overall design quality that made WoW so sucessful. They usually surpass it in one area or another (graphics, character customisation, whatever) but fall off everywhere else, often repeating mistakes that WoW made 4 years ago.I believe if they instead tried to make the game alot less about "personal skill" and alot more about which gear and talents you pick, that the entire market would be alot more satisfied with the game.