I'd like to suggest another theory: that Lucas never really had it at all. Personally, I think he was just an idea man, much like I think Gene Roddenberry was. He came up with wonderful concepts: a sweeping space saga, patterned after movies of another era; the Force, a wonderful way to link his space movie with the mythical tales of the past; the Death Star; a story of a rebellion against a tyrannical Empire. All of these are wonderful ideas. Yet an analysis of the films' histories reveals a damning pattern: with the single exception of Star Wars itself, the less George Lucas had to do with a given film, the better it was. The PT is just one big example of what happens when Lucas had things entirely his way. The result is crap. Over-done special effects, a disjointed storyline, horrible dialogue, stupid plot twists, etc.
Looking at the OOT is more interesting, in this regard. George Lucas wrote and directed Star Wars. The special effects were groundbreaking, the story uplifting, the dialogue was a little cheesy but delivered with real skill by the film's stars. Hundreds of talented people contributed to the film, from actors to cinematographers to modelmakers to conceptual artists to the composer. Honestly, how much of what we think of when we hear the words "Star Wars" actually came from George Lucas himself?
Next came The Empire Strikes Back, my personal favorite, and of many fans. And guess what? Lucas had much less personal involvement than with any of the other films. He didn't direct it, he didn't write the screenplay, he just wrote the story and executive produced it. The film had the best dialogue of any of the movies, the love triangle that was set up was well done, the effects were even better than in Star Wars itself, and the revelation of Luke's paternity, something which could have killed the film if it was done poorly, was very well done and just added to the film. God, what a great movie!
After that we got Return of the Jedi. While there is much to like about Jedi, it also has several problems. A lot has been said about the Ewoks, too much to go over here, except to say that they utterly emasculated the Imperial forces. The Imps, who are supposed to be scary, threatening, and Nazi-like, possessing the most powerful equipment the galaxy can provide, are smashed by anthropomorphic teddy bears armed with rocks. While the confrontation between Luke and his father, and the Emperor, were all well done IMHO, the whole brother/sister thing seemed a little too far-fetched for me. The worst thing about it is that it nullified the wonderful love triangle set up in Empire. Even before Ben reveals that Leia is Luke's sister, the whole thing is forgotten. Didn't Luke like Leia? One certainly gets that impression watching Star Wars and Empire. Yet in Jedi it's like that didn't exist. It's as if the sibling plot twist was invented to "justify" the love triangle's disappearing act. Am I the only one who thinks that Luke's decision to confront his father, suicidal as it was, would have been more compelling if he had just had his heart broken? Luke's nobility in trying to turn his father back to the Light was wonderful, but wouldn't his willingness to go to his own doom have been deeper, more compelling if he had lost Leia to Han? If Vader and the Emperor had tried to play on Luke's hatred, anger, and jealousy to try to turn him to the Dark Side? And wouldn't Luke's berserk, rage-fueled attack on Vader have been that much better if Vader had threatened the woman Luke loved? I know many will disagree with me on this aspect, but it seems to me that it could have been so much better. Now don't get me wrong, I like Jedi...but it's the weakest entry in the OOT.
And lo and behold, Lucas actually co-wrote the screenplay, Ewoks and all. He also wrote the story and executive produced. What a surprise. He wrote the PT, screenplays and all, and he directed all three himself. They stank, how shocking.
What about Lucas' other movies, you say? How about Indiana Jones? All three of those were directed by Spielberg. Lucas wrote the screenplay for none of them, and the only one he wrote the story for by himself was Temple of Doom.
And don't even mention Howard the Duck.
I kinda wish I had gone with Darth A-Hole instead.