From Entertainment Weekly:
GL: ..... You know, I never expect anyone to see a script [of mine], because they're terrible. I'm a terrible writer, you know, but because I'm directing it, I don't have to write it (?), I don't have to show it to a studio, I don't have to sell it to anybody. It doesn't have to be written for somebody else to understand. So I write a minimalist script that has hardly anything in it at all.
So, he knows he's a terrible writer, but that doesn't matter, because he doesn't have to sell his scripts to anybody.
WHAT ABOUT THE AUDIENCE, GEORGE? Don't the people paying to see your movies deserve a screenplay written by somebody who isn't, by their own admission, a TERRIBLE WRITER?