The Rebellion verses the Empire can be played merely as a combat game. The bounty hunters and smugglers leave wide possibilities open for games. For the same reason some people watch television, or read ooks. It's a form of entertainment, in which the entertainee is also the entertainer. Fans of IEE's get to experience it as though it were real life, yet also get to see it be experienced as a TV show, or a story in a book.
Fans can truly bring the story to life.
Role playing is one fo those things which truly defines an IEE as such. Obviously, any show or story worthy of being called an Imaginary Entertainment Environment will have a following that really wants to bring the story to life.