Now, I'm not saying I agree totally with what bro over there was saying, buuuuuuuuuuut.
Lots of things are popular that are bad. In fact, a lot of the time that is a hallmark of badness. Or whatever. As an example, I'll take books. Many of what are considered the greatest books of all time have never been read by the majority of the populace, and never will be read. Conversely, many popular book series, such as Twilight, are atrocious. This is the same with movies, shows, etc. Avatar is ridiculously popular, and it's pretty much just Special Effects porn. It's certainly not good by any sane standard.
I guess the thing that happens is that the average person is estranged from a lot of the better things. Basically, if it doesn't really make you think, and doesn't have any REALLY incredible characters, or storyline, it probably isn't GOOD.