Harry's winning the class cup for Gryffindor from Slytherin would have pleased a ten year old more than finding the Philosopher's stone.

And to a kid, the mean, bad bullies didn't win after all. Whereas I don't know about you, but I find taking away a prize from a bunch of kids like that rather harsh. Yet maybe it's good for young kids to be exposed to the idea that if you're a good person, you'll be rewarded, NOT if you're mean and stuck up to people who aren't "cool." Even Neville got an award. The scene still bugs me, but at least I can sort of see the rationale.