I always thought Lucas should have done just one 3+hour prequel movie, instead of a whole trilogy. I know that he would make more money with a trilogy, but I think a singular prequel movie would have done much better with public overall.

We didn't need a trilogy because I think the 3 movie idea poses so many problems. The main point of the Prequels was to show how Anakin turned to Darth Vader, and by having 3 movies and essentially waiting 6 years to see how he turned in Episode III, you have a build up of expectations which are ridiculous. Then you get so much filler time in the Prequels because Lucas had to tell his story in 3 movies, so you get alot of stuff that people really don't care about.

Lucas could have told the story of Anakin becoming Darth Vader in 1 movie (the same way Coppola showed Vito Corleone coming to power in Godfather II). Lucas could have told the story during the backdrop of the Clone Wars as the Emperor is ascending to power, and all the red meat could have been in just this one movie.