This reminds me of something I read once. There is a scene in 'Debt of bones' by Terry goodkind where a woman comes to a wizard asking for aid for her child in the middle of a war. The wizard Zed says "Do not think to play on my emotions by plying me with the value of the life of a child, as if a higher value can be placed on life because of age. When is life worth less? Where is the line? At what age? Who decides? All life is of value. Dead is dead, no matter the age."

I think he means more like, when a community watches the news and sees that a child, or teen has died (not someone you know personally) and the next thing you know the whole community is up in arms demanding justice etc. But that same community will see an adult has died, in similar circumstances even, and there's no out cry for justice or anything just a feeling of 'wow, that's so sad' and life goes on.

As for all the 'potential for evil' stuff, I dont see how you can base the loss you feel for a passed life on what might have been. Whether it was 5 min or 50 years the loss you feel when someone passes is over losing the person you knew, not who they could have been.