I think there is a reason, perhaps several! Something having to do with balance, the ripple effect that happens from very emotional events, the contracts that we set up before we get here, and hints from the universe that we are being helped by other intelligences not here on this plane. It's one of the things I hope to learn more about when I "die." :)
I figure I might as well wait until then since then I'll have a halfway decent chance of getting it right, and for now while I'm here the knowledge won't necessarily help the experience of being here, it'll just be a bit of data, and I've collected enough data for ten lifetimes LOL! ;)