It has been many many years since DDP was a cost saver, and serious math needs to be done to see if the "FREE" Dining is a cost saver. It is about convenience of pre-paying for meals, doesn't make it a deal.
When I first got the "FREE" Dining Plan I stayed Value and got DDP. Table Service included Appetizer, Entree, Dessert, Drink AND Gratuities. Over time it gradually became less and less and then we could only get QSDP. I went for 11 days on the QSDP and was OVER it in about 5. I worked hard to get value and kept all receipts. In the end (with work) I would have broke even if I purchased. It has absolutely no value to me. I want to eat what I want, when I want - and I save money.
The dining plans are offered to (1) Keep guests eating on property (2) Keep restaurants full (3) Disney enjoys the profits they make vs letting guests pay as they eat. Disney loves all those unused credits. And children that are paying for adults DDP, banking. Sadly restaurants will have to adjust their menus to reduce and dumb down so they can meet their profit margins on what the DDP will reimburse them.
On the plus, it is optional and if it doesn't work, don't get it.