I remember a takedown of the Hunger Games criticizing, among other things, the unrealistic food economy (which, at base, is the only real economy there is) such as the protagonist eating blackberries instead of selling them or trading away fish for a loaf of bread. I wish I could find that review again. The conclusion was that the backdrop is a set, not an actual living world, and I think that shows the real importance of worldbuilding. Unless the author thinks things through the world isn't going to work, and suspension of disbelief will suffer as a result.