If a person dies prematurely, if he or she is killed, have you ever imagined what would have happened to that person if he or she had lived a while longer?
I often watch movies and TV shows where no-name characters are killed for little to no reason, and I hate the lack of care for that. Each one of those people had a mother and father. Many of those people probably had a spouse and children.
But what gets me the most is something else I realized. Just one person is almost never killed when someone dies prematurely. If you kill a person, you have prevented the existence of possibly thousands of generations that would come from that person. If you kill a person, you have removed him or her from many people who loved and cared for that person.
There are always exceptions, but how many people do you know with no parents, no love interest, and no desire for children. If you kill a person, you single-handedly destroy the lives of many. And that is just one single person.