Disney obviously does everything they can do to keep you onsite -- free theme park parking for onsite guests, Disney transportation, DME, DDP, EMH, etc, etc, etc. The Mouse dearly loves a captive audience...and we all know why!
You might want to take a look at the relative costs of renting a car and eating offsite. Keep in mind if you do that, you don't have to pay "rack rate" during peak season for your room in addition to the cost of DDP. You may find you save money by getting a better price for your room, skipping DDP, and just paying cash for all of your meals...either onsite or offsite.
We're eating almost exclusively offsite on our May trip, after three years of DDP, and we're really looking forward to trying some of the excellent offsite restaurants (Charley's, Columbia, etc.).