The round was selected by the USG partly because it's a lot less lethal than other rounds and as such it does not inflict unnecessary suffering, relative to rounds that were commonly used in combat during the time that the AR was designed.
I am not trying to be contrary, but you are saying that by being less lethal (and we are not talking TASER or bean bag version of less lethal) it does not inflict unnecessary suffering. Which is the greater suffering, wounding someone who may eventually die from the wound or killing them straight out?