Broom Kid said:
Leia being around was a key part of Kylo’s redemption, and they specifically tied her dying to his redemption. It seems pretty apparent to me they only wrote Kylo’s arc (which essentially superseded Rey’s arc in terms of importance) the way they did because they worked backwards from what would redeem him, and they decided his mother’s choice to kill herself by reaching out to him during that fight would be the catalyst.
So they kept her active in the plot by recycling footage and writing dialog to mad-lib their way to the end of the 2nd act, specifically because they needed that presence to register just enough for Kylo’s redemption to pay off as intended.
If anything, Terrio’s answer when he was trying to explain why Rose Tico got so minimized seemed to hint that their initial “We’re not going to CG her” was an out and out lie, (it kind of was already, considering that training scene) and I wouldn’t be surprised if Han’s appearance was similar to how Superman’s mother is who showed up in Superman II once Marlon Brando was cut out. “Well, we can’t CG Carrie for this scene, let’s see if Harrison will do it instead.”
So even setting aside the fact her scenes aren’t particularly good (and it’s fairly obvious she’s not really acting with anyone in the scene, and nobody in the scene is really acting with her) the initial decision to make her self-sacrifice key to Kylo’s redemption, to justify repurposing a bunch of deleted scenes, is what hemmed them in.
It’s why the movie is so plot-focused at the expense of any real feeling or thematic coherence. They approached it like a puzzle first and foremost instead of really exploring what they had to work with at the end of The Last Jedi and building from there. If your primary story question (and they kept saying keeping Carrie is where they actually started) isn’t “Where do I want my characters to go from here” but “How do I repurpose deleted scenes so they’re so vital to our endgame that you can’t remove them,” you’re starting from a pretty mercenary spot, even if you’re doing so with the best, most honorable intentions.
That training scene of Leia was recycled from ROTJ. That was Carrie’s face and probably Mark’s as well. And the use of Han for that scene was crucial to his redemption. He had killed his father and that was the only way to redeem himself of that act. I hope you noticed that that scene mirrored the one from TFA, but ended how it should have the first time.
And I think they did work forward from TLJ. They picked up the story where TLJ left off, where the characters were, how they’d grown, and they continued on from there. I felt the story was very organic and did not feel forced or cobbled together at all. I thought some of their choices with the Leia scenes could have been done better. They missed a chance for Leia deliver some typical Leia expressions at the right times, but overall it was well done for what they had to work with. It was a fitting end to her character, much better than writing her out off screen. It was both important to the fans and the story for Leia to be there. It wasn’t forced, just very limited. It is one of the things I would edit if I think the film needs a fan edit. But the Kylo/Ben part I wouldn’t touch. I think that worked very well and it didn’t detract from the main character arcs or take much story time.