Honestly the game should just not show our characters in most cutscenes, especially since characters aren't fully voiced. At best we have long extended awkward shots of our character standing there silently with a neutral expression. And at worst our character makes some expression/motion (e.g., falling down in the intro when the red dragon appears) that doesn't mesh with the idea we have in our head for our character.

Showing companions' facial expressions and body language works because they have set personalities. Showing Geralt in the Witcher games works because, even though you can play him in a variety of ways, he has a base-level of personality and most choices are relatively in character for him. Showing custom-made PCs does not work because of the sheer variety of personality types players will come up with.

I agree that having alignment/personality-based facial expressions would be an improvement over what BG3 currently has. But the work required to make the system less immersion-breaking than simply showing less of the MC is too much imo. What if I want to play an initially-evil-then-turned-good MC? Will my character's facial expressions/personality change along with my choices?