The newest JFK SC has paid food options as well. I don't know of any others. Most (all?) AA clubs have food menus with items for purchase as well, so maybe that's where DL got the idea.
I actually kind of like the idea as long as they keep some decent free options as well (say what you want about my use of "decent" but I generally enjoy the soups). There are times when I want more of a full meal but don't have that long of a layover so have to choose between a restaurant or the SC since they prohibit outside food. As long as the prices and taste are competitive with other airport options I'd probably make use of the menu occasionally.