For young people, especially, humor is a positive response to dealing with life's larger dilemmas, such as loss, death, disease, unwelcome change. It's certainly healthier than anger and violence. Maybe because they make reading fun, not such a chore. But all kids love to laugh. And I love to hear them laughing.
Balance can be tricky.
I'm always cautious about crossing the line. It's risky using the lightness of humor to offset heavy topics. Sarcasm, especially, can be interpreted as cruelty or mean-spiritedness. I think it's the responsibility of writers who use humor to recognize its power. What we ridicule we legitimize and condone.