For me, that's something that would be nice to have but not a big deal if it's absent.
You're quite right, it's not a deal breaker. Would be a nice feature but I'd definitely cope without.
Since I play only one character, I like the option of changing, adding to and tweaking their characteristics...I like this topic...
Yes, hair in particular should be much more dynamic. Nobody keeps the same hair style all their life. And short of making actual growing hair, which would be a pain, being able to change your hair mid game seems like to best way to reflect this.
Gender? That's a bit strange, but then again it could be done with magic. Personally, RPG games should revolve around the Player's Character, and aesthetic decisions form part of the player's journey. Name and Hair should be the only things you can change without destroying your character's identity.
I included gender in the poll just for completeness - I would actually hate to see a sort of 'six change clinic' in Skyrim, just wouldn't be right