I think it's a mistake to even add classes.

[epigramx]

The game already has 12 classes and dozens of specs. It makes gametypes like 5man PvE or anything below 15v15 pvp absolutely broken because a handful of specs can dominate everything with their metas (even if large gametypes also have metas: they can't get as broken as small gametypes because e.g. even if you stack 5 druids in 20man PvE: you still have room for many more classes).

[Velerios]

Sorry, but as shown again and again and again and again is that new classes makes an expansion much much better; every expansion that didn't had a new class was a failure, and a new class always opens a new viewpoint to the game.

And yes, f*** balance; i rather have fun than catering for a few percent of players who wants to have a "balanced" game (something that really NEVER existed in wow, now matter how much people are screaming for it); adding the elitistjerks with their spreadsheats as devs was the biggest failure blizzard ever done. You can always balance the game later, but fun needs to come first.