CGI has made Lucas not try as hard on aspects as the storyline, but I think another aspect of it is that he has basically bought into his own "greatness" hype. He seems to feel he needs to listen to the actors/directors/other production people less, because if he came up with it, it has to be good. Combine this with a surrounding of the same "yes" people, and you have a show driven by only one person. If ESB was made today, I doubt we would hear the famous lines:
Leia: I love you
Han: I know

Lucas doesn't tolerate changes to "his vision" like he once did. The movies are weaker as a result.