Superman's need of his teammates is somewhat contrived due mostly to enforced mental limitations. The best explanation for this I've come across is his
World of Cardboard speech. Basically, he never allows himself to completely cut loose because if he did, he'd probably lose his mind and... I dunno... fly so fast around the Earth he somehow reverses its revolution, resulting in catastrophic global damage and likely destroying all life as we know it. This would be followed by a psychotic break where he hallucinates that this act of insane omnicide didn't really bring about the end of the world, but somehow "reversed time" so he could be reunited with the girl he has a crush on, and whose life he failed to save earlier. Something like that...
Oh, and he's also not the best strategist, he's not at all ruthless, etc.
But really, I'm with the OP. For the most part, Superman should be able to take care of any situation that arises that doesn't have kryptonite or magic attached. Reminds me of a fun debate with a friend where I stated that all the X-Men need are Storm, Professor X and
maybe Wolverine for covert assassination ops. Maybe. The rest of the team? Entirely superfluous.
