I like when games allow a button for Helmet off outside of combat myself.
That way you can get the best of both worlds. I am sure they will add something, DoS2 had it, and if not someone will mod it in for sure.
Glad to have found this post, I was searching of ages for the button to hide my helm and was wondering where hey hid the option.
I like the idea of hiding it outside of combat, maybe make it a toggle for each individual character as I like the circlet that Shadowheart wears and it looks nice in cinematics, but some of the other helmets not so much.