I've heard (am no expert) that goalie masks are also designed to deflect pucks away when hit in the front area like that, so you're not getting the full force of a shot on the mask. Richter got hit in the side of the head which isn't designed to handle that
Gary Warwick, famous goalie mask maker, (he's done countless masks for NHL's and goalies everywhere, Ryan Miller, Nabokov, Turco, to name a few) told me when he was doing my mask that Richter's injury was directly due to the fact that his terrible Bauer mask was a stock shell that wasn't corrected moulded to his head, and had a severe lack of padding. It basically fit 'loose', so when the puck struck it, it actually caused a much more significant impact with his skull, than it would have if it fit tight with thick foam (like all current masks do)
Gary was the one who made Richter's new mask when he attempted his come back, but once he took the knee to the head and got another concussion, he knew that was it.
If Richter had a mask that fit properly, and was padded correctly, he would have played many more years. Crazy to think.