A lack of perfection, the existence of tragedy, and the hope of a better world, allow humanity to grow.

If there is nothing bad, there is no reason to struggle, to become better, to improve.

If there is nothing good, there is no reason not to despair, to cling to hope, to improve.

Obviously this is purely philosophical, but as that very Futurama episode states (and many other attempts to tackle the problem of evil), “you have to use a light touch.”

Other excellent examples of this notion are found in the ending of The Wheel of Time, wherein a world without evil and a world without good are explored. Another fine example is in the second era of the Mistborn books, where a deity discusses finding that balance.