May I cut in?
I can see what you're saying about silly childrens story type comics and we're not saying they exist, but there are a number of comic book writers who have decided to take the comic book to a mature and more artistic level. I'd reccomend the works of Alan Moore for some great alegories on the human condition that can only be expressed via superhero story. You'll find rape, pedophilia, condemnation of society and government, anarchists, and darned good writing.
See, saying that ALL comic books, by definition, are silly superhero stories with no point is the same as saying that EVERY love story ever told is on par with Harlequinn Romances, or that EVERY Sci-Fi story is on par with Battlefield Earth, or that EVERY Drama is on par with Days of our Lives. It's a medium with which people can do whatever they want. Granted there are a number of people who go the silly superhero route, but there are a few hidden gems who've submitted some fine additions to the world of literature that just happened to be illustrated in a panel by panel fashion.