Yes, the helmets are mostly horrible. Fantasy armours usually end up as impractical artistic flights of fancy.
Mind you, the DnD armour classification has always been dubious as well. Their descriptions use a lot of historical terms, but relate them to jumbled degrees of protection not really supported by historical examples. Not to mention that someone early on seemed to misunderstand "brigandine" entirely, and instead categorise it as light armour under the invented name "Studded Leather".
