There's an MMO, Mabinogi I believe, where you start off as a child. As you level you age. There are things that you cannot do, like professions, and wandering too far from town, until you get to a certain level and become an adult. It's not too far fetched an idea.
Also, there's Wizard 101, where you're a kid in wizarding school. The game is meant to be kid friendly, and you don't really fight, you card battle, and when you lose a card battle, you're not dead, you're just sent back to town with 1 health.
I just think that in WoW, that is clearly meant for adults, giving peple the chance to act out inappropriate things with child characters is asking for trouble. Maybe, if Blizz spun off a completely seperate game, called Children of Azeroth, and it was a kid-like version of WoW that did not actually mix with WoW, like you're only a kid, and you focus more on pet battles and sparring and you don't venture too far from Stormwind/Orgrimar, maybe.