Here's what I just found at Mousesavers:
If you cancel your Disney resort reservation, you will be responsible for canceling any Advanced Dining Reservations that required a credit card guarantee or payment. If you do not cancel such reservations, the normal penalty will be charged.
So, there's the back door. As people figure it out and are willing to play that game to get the advantage, then I suspect Disney will have to make changes. What's stopping anyone from booking an onsite hotel just to get the dining advantage then turning around and cancelling the hotel right before penalty applies? You pay a refundable 1 nt. deposit - big deal! This is a flawed system imho.