I rreally have to agree that this, no matter how stupid I find the name (sounds like something from Medabots..), should have been implemented alongside RealID, also for forums, for everything, for Starcraft. There's been a lot of confusion and issues with this naming thing and tbh it's been a huge waste of time and resources that could have been way better spent if only the people involved had spend one afternoon of thinking it over.
"BattleTags will add a new way for you to make friendships and communicate in World of Warcraft. For example, you'll be able to create cross-game, cross-realm friendships with your BattleTag, similar to the way Real ID works now. We'll have more details to share closer to the feature's launch."
What exactly would be the point of a cross-realm friendship if you can't do ANYTHING with it?
Like I said "In their post they didnt say you'd get all the benefits of readID, just the communication aspects of it." You know, communicate.