for PVE raids anyone can be in charge, not just the prot warrior. PVP wise, its really what kind of playstyle that you prefer. Dont choose a class because its OP'ed or popular now, you might not like playing the class (e.g i hate playing my alt lock, using him to herb). From my point of view, as my main is a shaman, PVP is all about survivability (being resto) and burst (elemental/enhance).
For me i enjoy going into bg's with a 2hander and raid gear and just smack everyone silly. Granted, i die a lot, but hey 3k WF crits one shotting mages is one hell of a stress release after work .

....wtf aggro

T.T