Speaking as someone from a rugby-playing nation, where mostly players wear no protection except mouthguards and shin pads, American Football is spectacular but insane. Wearing protective helmets just ups the ante as players launch into each other with full force. In rugby, you don't tackle someone like that as you'll hurt yourself, and fail to stop the opponent. Rugby is a plenty violent sport, and has its own health…
Sounds like you know a bit about this - any chance you could weigh in on my question above? Does tackling serve a different strategic purpose in rugby vs American football (ie., not giving up an inch can be a big deal in US football), and could this also be partially responsible for the brain rattling quality of tackling?
In rugby a goal is to always keep the ball in possession. When you are tackled, you try and feed the ball back to your own side, who are (ideally) close behind you in support.
So yeah - yardage gain is somewhat meaningless for its own sake in rugby, as long as you maintain possession. If you maintain possession, the other team can never score, and you eventually will.
So the player's thoughts as they are tackled are less about preserving yardage and more about ensuring you'll end up in a position where you can feed the ball back to your teammates to maintain possession. Maybe that means less impact in the tackle.