Missed opportunity is more dramatic than actual reformation.
"The Hundred Dresses" is almost identical in storyline to "Each Kindness." All the kids make fun of a poor girl, and at the end, the girl moves away and the main character is depressed by what happened. Basically, the main characters need to see someone else suffer in order to grow, and they don't realize the opportunity they had until it's gone.
Message
Be nice to people for niceness's sake. Or, you never realize how much of a jerk you were until after the fact.