Star Wars and the Public Domain

Having stayed up until 4 last night playing Star Wars: The Force Unleashed my question returns to one I have often had in the past. Why is it that Star Wars so often does better in other formats than it movies.
The original movies are great and I don't even hate the new ones but still, having played Knights of the Old Republic 1 and 2 and read numerous books I have to say that I like the stories better there.
Part of that has to do with the iconic stature that the movies have archived. People know these universes and so there are many good authors who can write in it.
Second is that in the movies you have to try to reach a broader audience. A video game is a success with far fewer customers than a movie and a book even less so because of this you can add in the more difficult to understand points. In the force unleashed you begin as a Sith hunting down Jedi, it's fun but it would upset people if you had a movie like that.
Third is of course George Lucas. The man is a fantastic writer, but he should stick to that and industrial light and magic. Let other people deal with the individual Star Wars.
The other thing that it makes me think about is our current system of public domain, or more accurately the lack of it. I'm not saying that Star Wars should be part of the public domain, yet, but I am saying that movies the movies should be public domain at some point.
The argument of course is that he developed it so why wouldn't he make the money? That is fine but I think we should be encoring our creative people to have more than one good idea in a lifetime.