They have more taste, to be truthful, and only about 50 calories. They have almost no fat or sodium. Many flour tortillas are still made with lard and have up to 150 calories, almost 6 grams of fat and 140 milligrams of sodium. And that's before frying. There are low-fat versions available, however.
Black beans are great and can be easily spiced up.
Use the nonfat if you can stand it. If you substitute mozzarella for Cheddar, Colby or Monterey Jack, you can generally cut the fat by half. Tortilla chips are a worry. You have to have them for the salsa, but you don't have to have them fried. Here is a recipe offered by Cowin.