If you buy a game and it isn't a preorder you should be able to play the full version the moment you buy it. It is beyond ridiculous to pull that on a paying customer.
Restricting them to the starter area is horrible idea. It will anger your new customers and or flood your customer service to find out why they can't advance in the story. If they want to stem fraud just make the items you found in the 72hour window unable to be traded and prevent them from being able to talk in general chat. Let the people play the game they paid for.