Just for the sake of argument, what if we look at this from the other end. Does wearing a mask invite others to not be as careful when aiming? Maybe even encourage some to take head shots with the idea "He/She's got a mask on, they'll be fine" Pling!
And does only wearing googles or other proper eye wear encourage most to not take head shots on purpose or make an effort to aim elsewhere?
Personally, if I see that the guy Im about to light up has no face protection, I make it a point to aim low or if all I can see is the dudes head, I'll hold my fire and try to get a better angle.
However, if the same head poking up is covered in ABS and a pair of big ol' googles... then I don't think I'd be as merciful.