Unfortunately, there are those who'll always be looking for a bullet that produces that mythical "100% one-shot-stop" regardless of what part of the human body it hits. Ammunition design can never compensate for ammunition placement.
though what you are stating is correct, it doesn't change the fact that ammo does play a huge factor in hunting, self-defense, home-defense, accuracy with distance shooting, etc.
the law has always been something to the effect that you are firing a deadly weapon whether you are shooting birdshot or 00buck. I choose to always give careful consideration to the ammo I shoot with. I want the most out of an emergency situation since I have been made to make the decision to draw.