I think that there a two problems, that prevent optimistic sci-fi from being more prominent: 1. A good story needs a conflict and a struggle. "...and they live

I think that there a two problems, that prevent optimistic sci-fi from being more prominent: 1. A good story needs a conflict and a struggle. "...and they lived happily ever after" is an ending of a story, you can't go anywhere from it, therefore you cannot start a story with happily-ever-after. I'm not saying that it is impossible to create a conflict in optimistic setting, but it is much harder to do then in a dystopian setting that is rife with conflict. 2. I think that it is harder to make optimistic setting to sound genuine. We've been subconsciously trained by corporate marketing and govt. propaganda to treat anything overly-positive, overly-optimistic, dripping with honey and smelling like roses as "probably bullshit". While dark, gritty, dystopian automatically makes you think that "oh yeah, this guy is telling the uncomfortable truth that they don't want you to hear".