I find it curious what people expect from airport restaurants. Maybe it is just that I have been conditioned into accepting lower restaurant standards at airports than elsewhere, but consider the following analogy.

If you went to a restaurant that had live background music, would you expect to hear Van Cliburn playing classical music or Tony Bennett or Paul McCartney singing? Could an average restaurant afford to pay a top musician?

Restaurants are very difficult businesses to run in general. There is little demand for a high quality dinner venue at an airport. Add those two together and a business person would have to think long and hard before opening up a good sit-down dinner restaurant at an airport. I'm not saying it couldn't ever work, but it certainly would be a very risky business venture.