This is an excellent question. Oojason or SilverWook might know if something like that has been written up on here before. Some of the links in oojason’s first post might have more information on that.
theforce.net might have a thread about that as well.
It definitely would be interesting to see all the contradictions laid out though. I know WaywardJedi had a good post on reddit that compiled very George Lucas quotes regarding a potential Sequel Trilogy over the years going back and forth on how many there were and how developed (or undeveloped) the stories for them were. I’ll try to see if I can find it.
As you read this, you can see he jumps around a bit on what he says, but WayardJedi/Colton tries to unravel it all. You might be able to deduce that he had some very loose ideas, but on the other hand you could argue he changed his mind a lot too.
These quotes sort of make me think about how he has talked about how his story treatments for the new films were “thrown away”. But if you follow the development process as it was laid out in the Art of books, yes the final film is drastically different from the supposed ideas from the early treatments, but the “bullet points” of a lot of his ideas were carried over into the films. Story development is a normal part of any pre-production process. The early drafts of the OT films vary differently from the final films.
While some major changes were made for story reasons, like how Michael Ardnt had to delay Luke’s return because how his character sidelined the newer one, other changes were made just for aesthetic reasons (falling back on familiar ships/environments).
Lucas isn’t lying, but I also feel he is exaggerating just a little because they didn’t stick to his treatments to a T. I’m sure Lucas doesn’t care too much, but when he says they “threw away his ideas”, it puts the storytellers in an awkward position of having to deal with fans using his words to denounce their work, work that is directly influenced by Lucas’ original treatments. Maybe Lucas isn’t upset about it and is just trying to make light of it, but to others it comes off as petty, like he resents then for not following his ideas close enough and he is mad that they changed so much.
They definitely changed a lot, but it certainly wasn’t thrown away. But I think George made a point of this because TFA became aesthetically retro after he left story development, and he is big on visuals so he wasn’t happy with them relying on the old designs. Lucas’ emphasizes this in his interview with James Cameron, I believe, and interestingly enough this was also Cameron’s big critique of TFA after its release. Maybe they talked about it.
Wayward goes more into it in this post: https://www.reddit.com/r/starwarsspeculation/comments/6u44xu/clearing_up_some_misconceptions_about_the_art_of/