I mean, it's a big shopping plaza that has, historically, not been kind to anything but chain restaurants. On top of that the building would have to be extensively renovated or torn down by anyone who's interested because pretty much the only restaurant you could put in that spot as-is would be another 50s themed diner. Most people looking to open a restaurant don't have that kind of scratch, so it was either shitty chain or vacant building, not a lot of room in between.