The good thing about being on the DxDP is that you can try new things and you don't have to clean your plate. When I started getting dining plans, I first started with the regular dining plan. It was ok, but wasn't doing it for me. When I did the DxDP, I knew I had a winner. Like you, I don't order appetizers or dessert when I eat at a restaurant at home. However, when I'm at WDW, I find that I need all of that to fill me up from the activities of the day.
When I do the DxDP, I only eat two meals--breakfast & dinner. I do a character breakfast(something I wouldn't pay OOP for) and dinner at a signature restaurant. The snack is enough to stave off the hunger before dinner. I've never left a restaurant where I've left much food, if any, on my plate. As the PP said, it's liberating to know that you don't have to eat every single bite.
I've also done WDW without a dining plan. The one time I did(a long weekend), I found that I was hungry all the time, didn't eat very nutritiously(I was trying not to spend money) and wasn't pleased with my CS options. I'm going to WDW this summer and will use the TIW card and buy only what I think I want to eat. It will be interesting to see if I still want everything I would have gotten with the DxDP.