The motivation is avoiding injury. They think that somehow this will reduce injury. I'm not quite sure how, but that's the justification. b/c a receiving team is less likely to bring a ball out of the end zone if they get it at the 25 on a touch back? seems like you could figure out what the average return yardage is on kicks in or near the end zone and give the receiving team that yardage on a touch back. Fewer kick returns means fewer violent collisions. I assume that's the thinking. Isn't it just going to cause more pop ups/squibs around the 10 yard line, leaving the return man even more prone?