No, it doesn't depress me. Comparisons between versions of things is something I enjoy. It's like watching a movie of a book. They may be different, but even if they're both not great, noting the differences creates for me something which transcends the originals.
Granted, I know that's not the case for a lot of other people, but when someone tells me "that's Superman, but different in some ways", and these are ways I think I'd like (such as not being dark), this immediately makes me curious.
I agree that there is enough source material out there that people could make movies for years without having to tread over well trodden ground. Does it depress me? No. I can read books. I don't expect movie blockbusters to be terribly original.