When the old Supermans came out, there was nothing to compare it to, so they were awesome and everyone enjoyed them.
Now, you have other comic franchises and beloved characters getting the Hollywood treatment and it has made Superman's interpretation open for a debate that wasnt there in the past.
Lets get to the point.
Superman is damn near a God. Nothing in the known comic universe besides a silly green rock can hurt him in anyway. There is no fallibility with the character besides being somewhat of an awkward alien.
Until a movie embraces his god-hood, it will never satiate the fans who will drive its lasting value.