I doubt very seriously a family would all get desserts at a QS restaurant, yet many people figure those into their formula.
Also, keep in mind the gratuities. Because most people try to maximize the value of the plan by ordering the most expensive items on the menu, your gratuities are going to be higher than had you paid OOP.
Many people on these boards also like that their meals are prepaid on the dining plan - even though they know that they're paying more by being on the plan. The convenience factor is that important to them. In that case, I simply say to take your dining plan money and put it onto a Disney gift card; any money left over is money left over.
The plan used to be great. It was inexpensive; gratuities included, apps and desserts. Slowly Disney has chipped away at it. The price I believe is now about twice what it used to be and it offers a lot less than what used to be on it. For some odd reason though, people still look at it like the bargain it used to be..
Would you still be against the
DDP for those cases where it does save you money? While I agree it doesn't in general, in some cases it still does. On our upcoming trip for example, our 7 TS points are going toward high-cost buffets. And we didn't book the buffets
to get the cost up, we just picked where we wanted to go, then analyzed the costs of DDP vs OOP. We are saving about $150 (10%) on the DDP. We have, I think 11 restaurants, but putting the DDP TS credits toward the priciest ones, we come out ahead by having it.
I also consider, like you, that typical DDP vs OOP sites expect you to buy the most expensive desserts -- which we would practically never do. So I estimate a conservative $13 for QS points. And then I also only consider $4 on snacks -- not the inflated $5 or $5.50 that some sites think you can average. Even with these conservative values, I still come out ahead. It really depends more on the mix of restaurants you wish to dine at.
In our case, all your examples above including the "gratuities being higher" (which I agree with) are non-issues, because at a buffet your meal cost and gratuity are fixed.
Anyways, you seem to imply it can never benefit you... I tend to think more along the lines of it doesn't usually save money, but with the right mix of people and meals, it can. And for most ppl, if their cost would be "about a wash" then having it is a huge convenience, frustration saver, and vacation enhancer.
Also you have to factor in that the DDP can be prepaid with Target gift cards. Whereas I am likely to do this (and did so)... I am less likely to bring 30 gift cards with me on vacation for paying OOP or charging to the room and visiting the front desk to apply GCs. I have better things to worry about while on vacation. So this is an extra 10% we saved. So for us, our $1496 DDP price got us about $1650 worth of "what we would actually pay intead" dining, and we only paid $1350 for it. We easily got a fam of 5's meals paid for, at expensive restaurants, for $1350 -- and, we get a TON of extra food that we wouldn't buy otherwise (bottles of water and cookies with QS meals we can carry w us to give the little kids in emergencies!).
We also get mugs that we wouldn't buy (also not factored in for OOP).
I think each person should do their math and assess the value to their family, as the DDP, tho not the bargain it once was, is still useful in many cases.
FREE dining will almost always be better than an equivalent room discount if you max out the room. If you only have 2 ppl in the same room, the room discount would be better.