I also don't give a **** about the NFL, but in general I don't think parity makes a league better. Parity can be boring. I like it when the are good and bad franchises. I also like it when a franchise that has been bad for a long time becomes good. It's a much more intriguing story line than every team is the same and a random team wins every year. Of course, that isn't what happens, but it seems to be the ultimate goal of parity.
I think the NFL is more popular because it's easier to follow with a shorter season and only one game per week. They also market the sport better. I don't think parity has that much to do with it.