The thing that made them worth buying was that they were BtA and not BtC. If they took that step I'd be demanding a refund.
They might make them BtC for future sales (if they want to kill their sales) but it would be totally inappropriate to make the change retroactive. Heck, they left the known bugged/exploitable BtA huge bages BtA. If they weren't going to retro bind a store item with a known exploit then it would be totally in appropriate to bind a store item with no attached exploit.