After ESB, every movie has their flaws, and we can agree on about 95% of the time what those flaws are of each. Is it just a coincidence that the same exact stuff from the SE bother us? Han shooting first, the Jedi band song in ROTJ, and Hayden inserted into Sebastian Shaws place, every fan who wants the O-OT blood begins to boil when I mention these changes!
I guess the real question is did George know that he could put out a good, but maybe not great movies, and still make a boat load of money? The answer to that question is yes. Whatever we want to say about the PT, it was a financial success. Now it got creamed by the critics, especially TPM & AOTC, and many older fans like myself were disillusioned, but do you think Lucas really cares? He made his money, and though he may have alienated his older fans, there are newer ones who love the action and effects that will take their place.
Maybe ESB was such a success, that it wasn't worth it to try to make the perfect movie, and just make it good enough that people will like them. In saying this, I don't think Lucas sits there when he is writing a movie, and says, "I am ready to write an average movie, I don't want to make this good." That is an exaggeration. I just think that good sometimes, is good enough. Just look at how he resolved Leia remembering her mother, that is shabby storytelling, and to me is just being lazy and not creative. But I'm sure Lucas couldn't figure a way for all to make sense, and in the end just rely on the force.