Well, as much as I feel Lucas deserves criticisms for the prequels, I have a hard time placing blame on this one. Remember that the Star Wars films, for all intents and purposes, are independent films. Lucas isn't a bit studio mogul, and he certainly doesn't have the unlimited supplies of cash people seem to think he has, at least not in terms of making movies. Ever since The Empire Strikes Back, Lucas had been funding the films out of his own pocket. Empire was a huge gamble and almost ruined him. Kershner and Kurtz went WAY overcost and behind schedule. Eventually he ran out of money and had to run to 20th Century Fox in order to afford to get the damn thing finished. Obviously the results speak for themselves, and Empire did do well enough, but to this day it's referred to as "the hard one." While I do agree that the prequels are pretty damned bad movies, I think it has less to do with budget concerns and more to do with piss poor concepts, screenplays, and directing. The ominpresent greenscreen, while indeed a major problem, is secondary to the above.