THX-1138 was a great film, full of rich themes and interesting ideas. It was highly stylized, but at the same time the film really had something to say.
American Graffiti was the same thing. I defy anyone to watch the scene where Dreyfus is debating with Ron Howard and Toad about leaving for college and not feel the teen anguish, the uncertainity of the future we have all faced.
You see, Lucas used to make movies that made you think and feel. Then he made his little Trilogy of films. Star Wars was a sort of extension of Graffiti, a thematic relative - the youth yearning escape. It's a theme that worked in Wizard of Oz and countless films since.
But somewhere along the line, I think Lucas got too comfortable. There was no pressure on him, no suffering, and great art comes out of suffering. He was given free reign and I think it shows. The preqels made it obvious that he was a victim of his own machine and way too at ease. 'Phantom Menace' was just lazy filmmaking and on the nose.
I guess what I'm getting at is that Star Wars wasn't a fluke. Lucas had talent to be sure, and I think if he went the opposite route - personal films instead of blockbusters - we could be talking about him in a totally different manner...