Making this feature a core part of the game changes the "culture". Having third parties run the real money exchange made it a taboo, like in WoW if people knew you bought your character either for PvP or PvE there was always a stigma attached. But having the real money exchange part of the game can reduced, maybe even remove these stigmas and make it common place.
The culture change and hundreds of smaller game studios going "well Blizzard did it" is one of my biggest gripes.
Don't be fooled, this is nothing more than Bobby Kotick prostituting the heart and soul of Diablo gameplay for more shareholder profit.
Next time Blizzard should give gamers some fair warning so they can put some lipstick on; they like to look nice before they get f*cked.