+1 for The Michael Jackson analogy and everything Zombie said.

My own belief is that he knows, on some level, that he isn't as good as he wants to be, that he had to rely on others to make Star Wars and all of that, and he doesn't want to accept it. There was that one part in Zombie's excellent article on Marcia in which a journalist talking to her used the term "master director" to describe George, much to her amusement/frustration, and she said that he would love such a description. I think that moment really encapulates his issue with it. His redoing of effects, color timing, etc. seems to me to be a bumbling attempt to live up to being the "master director" that he wasn't. Maybe someday he'll accept his inadequecies.

Btw, @promus: I love that sig ;-)