They have such a program at Disneyland for a long time now and WDW for (seems like) 6-8 years. I'm forced to assume that legal / collections issues are a major reason that they haven't expanded it beyond those states. Right now, if they have to go after someone for non-payment, they're only dealing with Florida and California laws. And residents of those states would be the most inclined to maintain payments for the park access.
Expand it further and suddenly you have people living 1000 miles away who commit to a payment plan then close their bank account when they return home. With APs for a family of 4 running $2000-2500, it's really not that far fetched. Even if limited to DVC members, there will still be people who are a long way from their next trip who try to play games. I don't see how they could tie an AP payment plan into the DVC ownership from a legal perspective--just because both are "Disney" entities, they can't deny access to a deeded DVC timeshare just because you fall behind in payments for an AP. They are separate items.
Open a vacation savings account...transfer a few dollars every paycheck and boom, you've got your own payment plan. Money will be waiting when its time to buy your passes.