I think it show part development, one event doesn't justify the growth and final state of a person since a person will always be in a state of change and of presence, i think the story shows what was taken into consideration was "who matter at the point of times", such that "Gaara was of such importance than most others then" and urgency even thought every life is precious. However the pain arc did showed how easy it is to destroy one's mentality and cause another to break down. It is because of the people who are willing to give and sacrifice for the sake of the others, as well as the unwilling loss of lives of those that are precious to us.