However with that in mind, there are some compelling arguments that its due time for World of Warcraft to get a few age restricted servers.
For starters, take a look at what Second Life has done. They're a pretty successful venture, and have a lot of parallels to MMORPGS like WoW. They've created a server called Teen Second Life in which they do their best to only allow teenagers between the ages of 13 – 17 access. When you turn 18 you're moved up to the adult server along with all your gear and property. Of course this has the same pitfalls as any other internet site where you can fake your identity, but it is a start; and a good one since Linden Labs actively polices age restrictions.