The basic batting helmet style we now recognize wasn't around during most of his career. There were different designs knocking around, and increasing interest, but they weren't required nor was there a uniform standard.

In American football the adoption of the plastic/foam helmet and metal facemask changed how players hit/tackled each other over generations. It stands to reason that batting helmets change the risk/reward decisions for batters in baseball.

Walter Johnson hit 205 batters.