In that respect that is where I think Lucas has lost alittle of his edge toward moviemaking. If you watch ESB, then watch TPM, you wonder if it is the same saga sometimes? Sure, ESB is dark, and TPM is the lighthearted before everything goes to hell, but Lucas definitley miscalculated TPM, and some of AOTC with utter silliness that didn't need to be in the movie.
The Two headed announcer, all of Jar Jar, the fart jokes, Dex in AOTC, what was that all about? And C-3PO cracking jokes during the Clone Wars! Come on, this should have been a serious battle, instead you have C-3PO throwing awful one-liners every three minutes.
The reason these are bad, is even the Prequel defenders say, "Yeah the dialogue is bad, the love story isn't that great, and Jar Jar is overdone, but I still like the movies. If the people that hate the movies see it, and the people who like the movies see it, how come Lucas couldn't.
My opinion is after ESB, we were fully hitched to Star Wars, and everything he put out were gonna show up for it. Remember he told Kershner before filming ESB, "This has to be better than the original, if it isn't, there are no more movies." That to me showed that Lucas was determined to put out an A+ product, that resembled nothing of the original movie, but would still be as great.
Then in ROTJ, and I do still love it, but it is not as good as the Star Wars & ESB, the movie has recycled plots, character dialogue which is not as crisp as ESB, and the Ewoks! The ending is great, and that is what makes the movie. But you could definitely see that Lucas was satisfied with a product that was very good, rather than great.
In the PT, I think he felt the same way. I will make something good, but I am not going the extra mile to make it great, because in the end Star Wars is going to make a boat load of money.
Now this is my opinion, but definitely Lucas hasn't had the hunger to make a great Star Wars film in 25 years, oh well.