This seems like a bad idea. While not every WoW player is using the forums, i'm sure a good portion of them are. usually your real name is kept in the Account Info part for a reason, to keep everyone from knowing what it is. This makes it so everyone who uses the forum's real name will be out in the open. It's not the fact that you don't have to use the forum, it's the fact that they are forcing your real name to be viewable.
While it may be harder to find someone using just their full name, depending on the name. That doesn't mean everyone wants their full name known to everyone else. Think of it this way, i wonder how many WoW forum accounts are of people under the age of 18, or have their parents paying for their subscription, with the threat of Online stalkers and Pedophiles going after kids online, if the parents find out their child's name will be fully viewable to everyone, it may make them think twice about paying for the Subscription.
I heard blizzard is possibly doing this to cut down on rule breaking and such, which seems confusing since i think you already at least need a payed account to post on the forums, not sure if trial's can post, i never tried on my trial account. Which still makes all your activity tied to the account in question.
All together what they're doing just seems pointless and really unneeded.