I want to continue on this line - I hate that feature in other games. Not because it's not a good feature, but because it really means "We can't render what long hair looks like under a helmet, so here is your option"
But barring someone finally being able to render and mesh long hair that works under any headpiece, yes - I'd like this feature. The women-folk and their long hair under, say, the pirate hat make them look bald
Back OT:
Yes, helmets do nothing. Not even protect you in any meaningful way, so unless they have a bonus on them, they are useless.
Why we can't enchant hats , I dunno.