Certain productions should never be remade for a few reason. First, copies are almost never as good as the original. You see it in copies made on machines and in facsimiles - duplication causes something to be lost in translation. Although, with the updated technology and graphics capabilities, some productions will gain from being re-done, I don't believe this is one of them. Also, there are certain sentiments and connotations that are part of the context of an original release that cannot be recaptured in a remake or in the environment in time of a reproduction.
While I can enjoy a good run of Batman movies, et cetera I'm certainly not interested in watching a remake of every movie ever made. I think Mad Max could be left alone, but they're going to do it anyway. I'll be glad when Hollywood decides to favor originality again.
While many Hollywood remakes have certainly been terrible and are often considered unnecessary by fans of the original, I believe that film makers have the right to purchase whatever property they choose and remake it in whatever way they wish. The movie-going public has the right to vote with their wallets and choose not to go see a remake, but no one has the right to decide which films previously made would be regarded as "untouchable" for being remade. What criteria could you possibly use to consider one film off limits and another one acceptable to remake? That would be an impossible task, as art is simply a matter of personal taste.
While sometimes it is hard to watch your favorite movie be butchered on the screen in front of you, I don't think that we should ban remakes. I think that would stop some great filmmakers from coming up with some really great remakes. There are a lot of sequels that are actually better than the original.