George Lucas has great ideas, but he needs other people to shape and guide them, eg his wife's editing magic creating the Battle of Yavin.
Sometimes he accidentally gets it right. For example, lightsabers -- he gave the villains red sabers, and the protagonists blue sabers, which was supposed to be cheesy and on-the-nose. But actually it's not, because it has the dramatic effect of distinguishing opposing factions, in a stage-play sort of way, and is a form of artistic license. Lucas didn't realize all that, but he still had an accidentally great idea.