I think we're programmed for hardship. In my experience, human beings are happiest when they're working themselves to the bone. People are more likely to feel adrift and unsatisfied when they have too much leisure time. Obstacles are good.
For me, writing post-apocalyptic novels isn't so much about exploding helicopters and fifty-megaton doomsday bombs as it is about the pleasure of dealing with the best of everything that makes us human: cleverness, grit, loyalty, and self-sacrifice.