I understand your worries

But all in all: nobody will "force" you to wear that helmet, even if it's part of a Set and give more bonus value to some stats wearing all pieces of that Set.
An example of my female hero Primellina the Battle MAge Priest? (find a picture of her via the linnk in my signature

)
No helmet, no shield ! And only a two-handed sword or a bow she can find via loot of enemies, chests, barrels or quest reward . She only buy some yewellery items with a skillpoint on she love to use (only Amulets, Earrings or Bracelets).
Maybe in some cases using a one-handed sword, but only one (not dual wielding because I don't like that style of fighting, just me) and without a shield.
I don't care about less options to have more "boosts" wearing/using a helmet and shield too. Even on nightmare it is feasible (knowing I killed Amdusias this time in one trip, so without dying - I'm proud I did it

!)
But again, I understand the worries about the helmet