Unfortunately, kids don't (and can't) yet have the long view. That's why societies have greater tolerance for "childish acts," including in the legal systems. The amygdala, which is responsible for decision-making and impulse control, doesn't fully mature until we reach about age 25.
Heck, the child who was killed was still two years off from being a teenager, never mind in his twenties. His murderer was 42.
How many times were we asked as children (or asked our children), "Why did you do that?" or "What were you thinking?" only to get the shrug and very honest answers, "I don't know why I did it." or "I wasn't thinking."
If a child can get shot for playing ding-dong-ditch, what should be the consequence for the almighty sins of cutting across a neighbor's lawn, playing in the street, being noisy, splashing in public pools, and so forth?
How extraordinarily intolerant we've become.