The problem is not that it's hard to make but that some poses are unrealistic and make the model ugly from some angles. With a fixed camera, I can hide the problems. However, I think most people don't care if the model isn't perfect, so maybe I'll add a free camera regardless.
Well that particular style of Anime type 3D model often needs specific angles/lighting & shaders to not look really strange and give that whole uncanny valley effect.
It's essentially the lack of any 3 dimensional geometry for the nose & lip shape.
If each set-up has a static head position then you'd definitely end up with it looking off in a free cam at different angles. You could possibly set-up a follow -camera (with limitations obviously) function for the head & or eyes. I know I've seen this in at least one game... Can't recall what it was though.
Different shaders might make this better as you could end up with a more consistent look, but it'd be that uncanny valley vibe consistently. Granted some people seem to be fine with that given content I've seen.
Lastly you could shift to (or ad the option of) a different head/face style that is still anime, but doesn't have that issue. The best examples I can think of are Naruto, Fire Emblem: 3H & Dragon Quest X-XII. There are definitely other examples out there including mobile games that have solid model to take inspiration from.
I apologize if this is not what you mean by "looking ugly" it was mainly an assumption based on geometry and how sometimes things just look off when the geometry is wrong.