Well, here's a Scientology Horror Show: Travolta and Cruise are remaking "Butch Cassidy and the Sundance Kid." Another Must-Miss Movie!
Why do people do this?? Why remake classics?? Why not remake a movie that originally bombed and make it better??
Ugh. 
Because there are an amazing number of people out there who do not watch old movies.
No, seriously. It just never occurs to them that something that is "classic" might be worth seeing.
I ran across a case of this today. I've been letting the boss know that, if he upgrades to BluRay, der B and I are very willing to loan what we have, so that he and his wife will have something to watch. Well, I ran into said wife today, and she's a bit of a trophy, blonde and pretty, but fairly savvy. But when I told her of the discs that were arriving via post today, and mentioned
An American in Paris, she went blank. "Gene Kelly, Leslie Caron." "I've never heard of it." And I have every reason to believe that she was telling me the truth.
I've mentioned big stars from the days of yore to coworkers, and they ask "Who's that?" They haven't a clue. Totally off the radar. It's scary.
This doesn't mean that I think a Cruise/Travolta remake is a good idea. But it goes a long way to explaining the glut of remakes - "no one" remembers the originals!