@Matt:

The threat of the Burning Legion is greater than ever; the very fabric of time itself is under attack; Illidan schemes within his black temple, and we go and play a game of gladiators under the watchful gaze of a goblin in a tuxedo for the benefit of the empty stadium. At least with battlegrounds they made a half-hearted attempt to patch up Unreal Tournament with some lore. Arenas are a joke. Having said that, I hear that the new comic book with the King of Stormwind in it involves arena tournaments, so maybe Blizzard is belatedly attempting to make it fit.

Either way, it's still detrimental to the game. When classes and abilities are balanced around very specific 5v5 combos then the whole game suffers, because what balances a lock in a team of pally warrior mage and shaman against an identical team is not necessarily balanced for anything else in the game. We've seen this time and time again, and I really hope that the expansion is going to wipe the slate clean and return PvE to its rightful place at the heart of game design once more. By all means have arenas and tournaments, but don't make the game revolve around them. They are, after all, an addition to the game, not the game itself.