If they price the DDP to be profitable on its own ( fee per day > expected use ) it makes sense to offer it to
DVC and AP.
If they price it at a discount to expected use - then it only makes financial sense for Disney as a tool to sell room and ticket packages and prop up cash occupancy rates. So offering to DVC would not be profitable.
Basically, if it is offered to DVC it may not be worth it to DVC members. I know some say it is a convenience. I could understand that thinking back when the tip was included as sort of a leave your wallet at home all-inclusive cruse ship like experience. But I don't get the convenience of having to look for icons on the menu, find and ADR participating restaurants and restrict yourself from offsite or in-room delivery options. I have weird eating patterns at Disney paradoxically I tend to not eat as much on vacation. I hate crowded restaurants so I tend to grab Epcot festival offerings during off hours in kind of a round-the-world tapas thing more than sit-down meals. DDP would not work for me other than resort days.