Because Star Wars did it before?Mumorpuger said:Why would you want to tarnish a good story with space wizards?
It is no secret that Lucas was heavily inspired by samurai films when making A New Hope, in particular The Hidden Fortress, another classic film by Akira Kurosawa. The original script for episode IV even strongly resembles the plot of that movie.
Basing a Star Wars movie on Seven Samurai is not necessarily a bad thing in and of itself. It all boils down to whether the director can make it work.