Also if someone haven't picked up MoP yet I doubt they are playing WoW for the story otherwise said person would have bought the expansion months ago. I don't think Blizz has to worry about people just getting into the intro GL story now. Plus how would you even do the transition? When the person gets exalted? That takes forever and weeks of dailies. They wouldn't be able to do any of the current new content in the zone (new dailies) until they got exalted which would suck even more for a new player or even old players who didn't get exalted. It would be a gigantic gate.
Were getting pretty off thread topic though so lets agree to disagree lol.