Going back to the main subject of the armour not being present under their necks and shoulders. Well, there's a pretty obvious reason why they didn't have any.
Reason: It's because they couldn't have any!
Heh, if they had, they wouldn't be able to run and use their hands easily to fight with. Also, they wouldn't be able to turn their heads if their necks were covered in metal.
Even in Medieval times this sort of thing was thought about.
(Wow it's been quite a while since i posted anything on these forums