Welcome to the boards, Mike, and thanks for listening to the show. It's nice, yet weird, to know that people actually are hearing what I say in other places on the world.
I, personally, feel that super hero movies fail most of the time because unlike the comic medium, movies are more a commodity for the masses. The masses that make up the movie going public aren't worried about subtlety in the stories they are watching. If they are watching Kick-Ass, they want see people getting beat up for an hour and a half and not the side story of how being a super hero effects Dave Lizewski's real life.
Most of the time, movie makers act like the story is getting in the way of the action sequences. Take GI Joe. Take the title away and you have generic special ops movie #453. That movie didn't need the GI Joe brand to add to it. It needed it to sell the movie to people that wouldn't have gone to see it if it didn't have the name brand behind it. I'd say most people that liked GI Joe, would have liked it even if it wasn't called GI Joe. That's why there is alot of "comic book movie fatigue" and alot of deep sighs when the new comic movie gets announced.
In the end, it's about quality and staying close to the subject matter. That's why everyone I know is hyped for Thor. That's why Spider-Man was (is) cool. And that's why GI Joe sucks.