The thing that would be difficult for a builder to overcome here is that feeling of a basement feeling kind of like a dungeon. It's difficult to get enough natural light without ending up with a "raised ranch", and walls that don't feel cold. Make it into a large rec room and a place for the kids where they can be noisy and run around without tripping over storage boxes... Then some people will buy the idea of a basement, even if it does add $20-$40k to the price of the house.
I would!! I'd love it! A basement would make a GREAT GAME ROOM for the kids!