5. Grand Arguments are not good for characters
I feel like the main reason Shadowbringers worked and was as successful as it was is that Shadowbringers is a story about people, it's trying to explore the characters as individuals in the face of the horrors surrounding them. We got to empathise with them because they had depth, they had interiority, they had personality. Humans love that! We love reading stories about people, where we can relate to them as people, where we can see their flaws and contradictions, where we can see them succeed and fail on their own merits and act for their own reasons.

This expansion, on the other hand, is extremely moralistic. It's not trying to be a story about the characters, it's trying to be a story about imperialism and the difficulties of ruling and then a story about grief and having to let go.

Now, to get this out of the way: it's bad at doing that. It's really, really bad at doing that. The reason, in real life, here on Earth, that we should let go of the people we lose is that we lost them. If we had a way to keep them, then we shouldn't let go of them, actually. If you want to write a story that's about having to let go, don't write one in which you're killing the people you're meant to be "letting go". They're still right here. We don't need to let go of people who are still right here, this is like saying, "oh, grandpa is 65 now, we should let go of him". If you want a story to be an allegory, you need to make sure your allegory doesn't get completely destroyed by the object-level facts you decided to depict in the story.

But more than that, in trying to be an allegory, the story murders the characters. They are no longer individuals, they are vectors for their arguments. You get Wuk Lamat and G'raha Tia and Erenville and Krile all saying the exact same things—after a token show of reluctance, here and there—with zero nuance and zero disagreement and zero context from their own personalities and beliefs. There is no struggle between them, because for this story, they're not people, they're storytelling devices. They are tools to convey the aesop.

Except that they're characters, too! We like them! We've met them! They have (or had) personalities and quirks! Krile wasn't sassy even once in this whole story! Where's the Krile that messed with Estinien that one time, pretending to have an Echo vision about him, to convince him to join the Scions? Where's the Krile that pushed Thancred's buttons to figure out how he felt about Minfilia? She's dead and gone, and a demon of some kind is possessing her body and using her as another way for the story to tell the player its argument.