He ruined them by being more interested in the effects than the story. Also he'd rather sell tons of terribly made merchandise and spend time re-releasing the same movies over and over. When it really came down to it all George Lucas has is Star Wars and he's milking it for all its worth. Now Disney is clearly going to do the same, because hey, its Disney, but in any future installments of films without just the sole input of the Bearded One maybe they can get some quality back in the films.
That's the thing I like the most, while Disney doesn't always put out gold at least there can be some fresh perspectives for Star Wars.
From my understanding, Lucas felt constrained by the special effects technology of the day, so when he had a chance with modern tech, he went wild. I've always been a special effects junky so the PT was a thrill for me.
I never expected any "haughty" science fiction from these movies. They are what they are. Some people just like their original popcorn flicks from the modern popcorn flicks.
I'm not so sure that an unlimited SFX budget is such a good thing.. you can show pretty mucn anything your mind conceives with digital technology these daysbut i believe it makes you lazy.
Lucas was forced to improvise in the 70s because the tech wasn't ready for his visions but did it take away in any shape or form from the movies? Movies should tell a story, have characters act in them but where's the story in a 20 minute speeder race whose sole purpose is to free one of the main characters so he can tag along with the others?
It's about 15 minutes longer than it needs to be.. it's just eyecandy and that's what's wrong with Lucas.. for me.
He turned from a storyteller to a showman.. he replaced story with flashy effects and action scenes and thus did a huge disservice to his movies. The new movies are just a collection of CGI set pieces and action scenes to wow you with the visuals but the characters (and thus also the actors) were very bland bordering on terrible.