I agree.
Even if he does, I imagine it will be when he's by himself and those scenes probably won't last long.
^Yup, this is exactly what I want.
There are scenes in Goblin Slayer where he does take off his helmet and armor, but his full face is always obscured.
Or like Dredd 3D. We never see his whole face even when his mask is off.
It reminds me of the old EU Boba Fett stories. This is back when he was still Jaster Mereel. Whenever he was alone he'd take off his helmet, but he always made sure to have it on when someone came into the room or to speak with him. He didn't like to be seen without his helmet or armor.
Also, I'm not saying this is the route they go, but I will have all the more respect for Favreau, Pascal, Filoni, etc. if they do.
IMHO its not about being a superhero. It's about how they want to maintain a level of mystique and intrigue for the character.
Also, it's about creating a character who can get the full characterization and performance across despite wearing a helmet the whole, masking his face, eyes, and emotions, since those are usually crucial tools for an actor's performance. Based on what's been shown, I think Pascal is pulling that off in spades.
Also, Mando might have specific reasons for always having his helmet on. It lets us the viewers fill in the blanks in this case rather than the story spoonfeeding us everything.