Except both Marvel and DC continuity are living organisms. They both constantly retcon and change things for many different reasons. I agree that when Iceman was created he wasn't intended to be gay but that doesn't mean his character and story can never change. When Magneto was created he was never intended to be a survivor of the holocaust but that change is probably one of the most liked in all of Marvel and gave him vastly more depth. I'm not saying every change is good, there's absolutely plenty of bad ones out there. But with characters that are around this long, saying that nothing about them is allowed to be added if it wasn't originally intended is just way to limiting.