I wish that this preference for the dark and serious wasn't mistook for maturity or importance. It just shows a poor utopian imagination, the idea of utopia was the joy of classic Sci-Fi and Star Trek.
Anyone can create a dystopia, it takes a real visionary to dare to create a world they'd like to live in. This is something that Sci-Fi, as yet relatively untouched by the smug centrist semi-nihilists, still has the potential to foster.