I think the argument to be made here is that Lucas was great when he had people around to tell him when his ideas were fucking dumb.
He's never been in a position or accepted any position where he didn't have final creative say. It's why he quit the Disney Ep. VII production. I don't think he knows how to handle it, honestly. The only reason I think he allowed Kershner to direct with his own creative vision is because he respected him, but it's obvious now that he differed with the direction he took the film.
Keep in mind, he still produced and managed Empire and ROTJ. He had the least amount of input in Empire, due to some health concerns as well as taking into consideration critical input from his cast (particularly Ford). That film was the one that had a majority of it's direction and script handled by others, like Kasdan, Kershner and Brackett. Although Lucas did write the overall
story for both films, so he definitely deserves tremendous credit.
The difference between Empire and A New Hope is simply directorial style. Kershner wanted a more serious, darker movie, to appeal to an adult audience. Lucas wanted a family friendly movie for all ages. You can see how ROTJ tries to be both simultaneously.
Also, keep in mind, Lucas has said on more than one occasion that
Empire Strikes Back is the worst of all
6 films. So that tells you what he thinks about my favorite Star Wars movie.
He's had some great ideas and some utterly awful ideas. The prequels are entirely the latter (see also: Indiana Jones and the Kingdom of the Crystal Skull), but it's no secret that he had to be talked out of some really terrible ideas in the original trilogy as well.
Indeed, but again, he was in final creative control. He chose to collaborate with people that he had some personal relationship with and with whom he trusted.
Now, the prequels were all him, and I totally agree with you there; he fucked up. He should have had more creative minds in the process. But he was disappointed with Empire's tone and direction and didn't want a repeat of that. He has made his disappointment with Ep.5 and to a lesser extent Ep.6 known for some time.
So again, that is the vision of Star Wars that
he has, and frankly, it's just as valid if not more, than that of some fans.