When it comes to the debate about what can be called science fiction, Ryan Britt nails it:
"... when it comes to the definition of science fiction, there's not really a moral imperative here. Culture changes the way we use language, irrespective of whether or not people like that change. Old-guard literary SF people don't have to like the new, more broad definition of science fiction, but they do have to live with it.
And I find this an interesting concept to consider.
Unlike a mystery or a romance, science fiction doesn't have story-telling rules. Instead, sci-fi can encompass all the narrative genres. Shows like Star Trek or Doctor Who can do horror, comedy, romance, and mystery, all with the same characters in the same setting.