Yeah, builders usually go cheap on the HVAC systems. My house is 2 floors, ~2,800 sq ft (I'm not saying that's big and not interested in sq ft wars), but has only two air returns downstairs, and one upstairs. At the house I used to live in in NY, every room had an air return. But adding such things isn't exactly easy to do on a finished house, especially upstairs, and even downstairs when you (like me) have no basement.