A character is only as good as the writer. There have been just as many bad or lame Batman stories as there have been Superman or Spider-Man stories. Need I remind people of Azreal-Batman, Ace the Wonder Dog, or the entire homosexual undertone controversy between him and Robin (a theory I don't buy, but it's there). Also, Batman's no more trapped in his own mythology than the other characters. He's not going to develop anymore than the other iconic characters. He's always going to mourn his parents, he'll always outsmart the bad guys, he'll never kill the Joker (and God knows how many times I've heard the "I can't kill them because I'd be one of them..." or "I should have killed the Joker a long time ago.")
My point is, he's just as cliche and stuck in his mythology than Superman.
Superman can be an interesting character, but I'll admit that (like Batman), there's been a lot of people that have written bad stories about him. Of course you're going to think that he's a boyscout and outdated, but that's assuming that a moral character can't exist in this world. I would say Superman should exist moreso in this world because he's such a moral character. He has all this power and yet hasn't been corrupted. He's a country bumpkin just trying to live up to his own reputation. It kills him that he can't save everyone, even though he knows he can't be everywhere all the time.
Also keep in mind that, in my opinion, he's a character loved primarily by people who are a big kid at heart. He's an optimist or an imaginative person's best friend. The kind of person who dreams of flying or maybe playing catch with their super-powered dog in space.
Anyway, I could rant on and on to the point that this becomes ridiculously tl;dr. I'm not going to convince you, just like you won't convince me that Batman isn't just a scarred little boy lashing out a the world with his toys. Yeah, Superman's a boyscout and I love him for it. I could recommend all sorts of things that might, just might, convince you otherwise (All Star Superman, Superman: Secret Identity), but it won't change how you think, so I don't see why you need to bring it up in the first place other than to troll Superman fans like me.