the reason i think is that side profiles are not often shown in anime, it is usually at an angle because most anime styles don't lend themselves well to side profiles.
This is how they are usually drawn. Actual human faces don't work like that. The mouth is off center an pushed back. IF you were to see it from the front how it looks from the side, it would look like this:
The Author is actually doing a more realistic portrayal of the human face and that is why it looks weird to you.