Dont see whats wrong with that logic - ppl need new chalenges, esp. at the end of wotlk, ppl want something new to try. New will come in form of Cata, but until then you cant blame them for wanting something else.
Arms warrior - extremely fun and demanding to play in raids, unlike furys which are so "empty" and boring
Also , I think WoW dont need bible - "this tree for pvp, this for raids, this for leveling" - let us choose what we want and have fun with