Baseball Rule Change Timeline
This timeline shows that the runner out if hit with batted ball goes back to 1880, the same year the catcher had to catch the third strike on the fly. That year it took 8 balls for a walk instead of 9. It leads you to think that it was common strategy by the offense to try to get hit with the ball to keep the defense from fielding it. It seems to be one of those rules everybody seems to get, "Hey, the ball hit the runner, he's out" -- not much argument from anybody there. At least until the myth of string theory came along.