Yeh this one has been on my todo list for a while. The reason it hasn't been done is that it messed with the character's textures when I tried it before - the game got confused as to what it should be showing - costume, armor helm or just head.
I'll take another look at it though because a lot of people have asked for it.

Yay~! Finally I can turn off my costume hat and show mai gorgeous hair lolol
Er... if I click show costume but not show costume hat.. it does work that way right?

Haha nice Thanks Sedy

Yep - I wanted it to be Hide Costume Hat but since everything else is Show, I kept it that way.

thanks, we will hope