Yes, it's easier to captivate attention by evoking primal instincts - avoid predator, find food, reproduce, etc. These stories stick around in your head, the memetic survivors. They are easier to feed off.
But "Happy" doesn't mean a perfect utopia. The entire "classic" Star Trek is set in a utopian future, yet with plenty of space for intrigue. Usually a commentary on a contemporary problem, with a "happy ending" that's supposed to show us the road to a better solution, rather than a bland "forever after".
Even "First Contact" (a zombie/survival horror) is spun around the theme of "this is the history/future that we're saving".
