Why the Prequels were different than the OT (and not because of CGI)
While we're all aware that the story style is a little bit different in the original trilogy compared to the prequels, there was a hidden factor in play, one that you'd only find out if you looked into the history behind the OT vs. the prequels.
It's not disputed that Lucas is a very creative guy, and had a unique vision of a galaxy full of wonders. His hand is in all of the first six films. What you didn't see, is that while he has a good set of ideas, he isn't always good at implementing it. He had equally creative people helping him with his scripts and movie-making behind the scenes back in the 70s and 80s. I remember reading that the original cut of "A New Hope" was awful, and it was because of his [at the time] wife that the re-cut was the awesome film we got in the theaters. She knew he had a good idea, but she cleaned it up a bit, as did others.
The problem was, when Lucas was writing the scripts and putting together the film prequels, he didn't have those creative people around anymore to help him make the stories better. He also tried appealing more to children than to whole families. He didn't have a lot of creative, smart people at his side, helping him come up with better ways to tell his story than what he had. So while the prequels aren't the worst Star Wars films ever made (the ST got the crown on that one) they aren't as good as they could have been.
What should be noted, however, is that many people still like the prequels and still talk about them, and those three films launched inspiration for a lot of other Star Wars-related ideas. We finally got to see a newer, freer galaxy the way it was before the Empire took over. We got to see a world where there were many Jedi, not just a few hidden in the wilderness. We got to see a rich, colorful, more expanded galaxy than even the OT could show off.
It led to many more books, more interesting sci-fi film ideas, and even an new franchise took off in the early 2000s relating to Star Wars (Knights of the Old Republic). The extensive use of interesting costumes made other films step up their game when showing off costuming talents to the audience. People even got to see new ways to do space battles and new starships. The very first all-CGI character was introduced (much as people hate him). How many movie studios do you know about that have been able to achieve the same thing? The best part was finding out there was more than one way to show how Jedi and Sith look and fight. Nobody had ever seen a double-bladed lightsaber before Episode I, or seen more than four force-users in all of the OT.
Can you say the same about the ST? Not only did they not break new ground in anything, they did more to attempt to destroy the franchise and piss off the fans than the prequels ever did.