It would be immoral to genetically engineer suicidal depression, and it would be immoral to engineer the desire to die in this society, where it cannot easily be fulfilled.

But imagine that puberty, instead of leading people to want to have sex, led us (or some of us) to want to die. While this might be as bad as puberty currently is, with new hormones and great confusion, hopefully a competent genetic engineer would actually make it better. No depression here, but looking forward to becoming an adult, with all that this entails. Presumably the engineer even has some purpose in mind, but even if not, I'm sure that society is more than capable of making one up.

There must already be a science fiction story out there with this premise, but I don't know one.