I can give Lucas a bit of slack for the lucklusterness of the PT and ROTJ, since he was ultimately just trying to make pulpy Flash Gordon-esque adventures, not high-art movies. ANH and ESB, however, were so good that they’re generally considered to have entered into the realm of high art. He then fell into a trap where his subsequent films were expected to be masterpieces as well, and I agree that he could have definitely done better on them. But since he really knocked it out of the park on his first 2 SW films, fans’ expectations were higher than his.