We have found the same thing--the savings is not huge.
However, when we did the DDP vs. paying OOP, we ate a lot better. We normally would try to do CS meals, snacks, and a few TS meals. And, when we went to TS meals, we were always looking at the prices to try to cut costs.
So, it may not always be about the savings as much as it was nice to go into the restaurant and just order, without worrying about the price. And, when I got my dessert, I didn't feel bad about eating just a few bites. Had I been paying OOP, I would have never ordered it--or, if I did, I would have eaten all of it!
For budgeting purposes, it can be a good thing.