I imagine no data makes games unsexy to most people for preservation. That and the woman's toes in the Computer Space flyer. Those crusty shits don't help. I think explaining to most people that they were a series of weird old chips with no data would probably melt a lot of brains as well since it goes against everything anyone has ever been taught about video games. But I have no idea the real reasons they were left out, though the tech for much of the stuff shown was developed in the 70s.