We just returned from a trip 3 weeks ago. My husband, myself and my grandchild who is an adult per WDW. I really considered getting deluxe dining since we would not have enough credits for our planned sit down meals. Paying for Deluxe dining would have cost $1422. Instead I purchased a TIW card with my AP. We bought 3 mugs (because we like them as sovies mainly) ate at Flying Fish, Citricos, Artist Point, Whispering Canyon Cafe (breakfast and dinner), Raglan Road, and Sci fi. We also were at POP for 3 days of the trip so we could use it there for counter service. Including all meals, all snacks, all tips and taxes, and adult beverages we spent a grand total of $889.57 plus the cost of TIW = $964.57.
We saved $457.43 by not purchasing deluxe dining and everything was included and we were able to order whatever we wanted and bought some snacks that were not included on the dining plan.
For me and my family it is a no brainer. I will not purchase the dining plan. I won't even take it for free since the room discount is more important to me.
I had free dining way back in the beginning when it covered apps and tips and we needed to pay OOP for one sit down and left 7 CS meals. It just does not fit in with our dining.
As far as having it "pre-paid" and not worrying about what you order the reality is you did pay for it; just not when they delivered the bill.
Edited to add: regular dining would have been $828. but we would have to pay OOP for some of our sit downs plus tips, alcohol, etc. There was zero savings for our family.