It begins with Disney as it’s very clear in retrospect there was no plan for the trilogy apart from playing to our nostalgia while regressing the accomplishments of the older characters. Even George said as much in the now infamous Charlie Rose interview. I also remember a post on Reddit about the whole situation post release and how one main point was the individual mentioning J.J. and Rian not liking each other. This had been said before by individuals with Collider but it’s becoming more and more true. Like the information about how John and other members of the cast preferred working with J.J. to Rian. The more information that comes to light, the more I see credence to all of this coming from the top at Disney. It was there decision afterall to throw out George’s story treatments and J.J. and company were part of this decision by the way Bob Iger disclosed things in his book.
I think The Rise of Skywalker is a result of both J.J. and corporate meddling.
Look at how much the film actively tries to retcon The Last Jedi.
Look at how Daisy confessed they weren’t sure what they were going to do about Rey’s lineage even during filming.
Look at Kathleen Kennedy’s comments to Rolling Stone before release.
“Well, I wouldn’t say you ever get to a point where you just go, “That’s it.” It’s a constantly evolving process. I mean, there’s still little things that we’re trying to get exactly right, right now. You never stop the storytelling iterations that go on in making these movies. But we know what these previous eight movies are. We know what that story is. So in this movie, we’re taking all of what’s come before, and we’re trying to find a satisfying conclusion. And I think we have, and that’s something that we can only depend on our instincts to arrive at, whether or not we have. And then we have what I would call the family and friends that you pull in and you show things to when you try to get some kind of feedback, and make sure that you’re making sense and that you’re delivering on the things that you intend. That’s something that we’re still talking about right now.”
And finally look at Ben Burtt’s comments about being kept out of The Last Jedi.
"I don’t know if there’s bad blood. I was just never consulted or hired to do any of them. No one’s ever told me why. No, I was told–on the new regime, I was just told, ‘Just stay in your room and make sounds and just send stuff to us. We’ll decide what to do.’ "
“It wasn’t always easy working with George, but at least it was one voice. And you could get his attention and have your say and present something and get a yes or a no. But it was just one person you had to get past. Not banks of different people who want to have a say.”
It’s all a result of too many people trying to have a say and no longer there being a singular vision but a committee trying to please everyone without understanding context of themes and ideas they’re trying to incorporate into their stories.