Actually, Buffy did have sci-fi elements in it. Season 4 was pretty much 80% sci-fi, with references to both Clockwork Orange and The Prisoner - classic Sci-Fi shows. It falls into the category of sci-fantasy. Also in the first season - we had sci-fi references such as I Robot/You Girl, and the one about the Prey Mantis. There was TED in S3, along with Bad Eggs (clear reference to the Robert E. Heinlein novel about Body Snatchers - not the better Jack Finney novel) and we had the whole Professor Walsh storyline.
So yes, Buffy did have sci-fi in it. In fact it did the whole human robot thing before BSG did, with both I Was Made to Love You, and Robot Buffy. Warren and Adam were both science fiction villians not gothic horror.
Whedon liked to blend genres - romance/science fiction and horror. Angel the Series also had elements of science fiction in it - with Fred and parallel string theory. I know because I was on a fanboard that had actual scientists play with the science themes in both series.
And most horror falls either within science fiction or fantasy. I know, because I hated both as a child because I didn't like being scared, it wasn't until Star Wars popped up that I wasn't getting scared by sci-fi and fantasy shows, they always had monsters.
Even Firefly had elements of horror - the Reavers.
So, you can't neatly categorize for all shows. What distinquished Buffy from Twilight, Moonlight, Vampire Diaries, True Blood, etc - is that it contained elements of both gothic fantasy and sci-fi, reinventing the vampire genre as a result, creating a new category known as sci-fantasy with urban sci-fantasy. Granted the science isn't always accurate, but that's true of most tv shows. 90% of the science on Caprica, BSG, Star Trek and Doctor Who is far from accurate.
A few quibbles...
So yes, Buffy did have sci-fi in it. In fact it did the whole human robot thing before BSG did, with both I Was Made to Love You, and Robot Buffy. Warren and Adam were both science fiction villians not gothic horror.
Whedon liked to blend genres - romance/science fiction and horror. Angel the Series also had elements of science fiction in it - with Fred and parallel string theory. I know because I was on a fanboard that had actual scientists play with the science themes in both series.
And most horror falls either within science fiction or fantasy.
I know, because I hated both as a child because I didn't like being scared, it wasn't until Star Wars popped up that I wasn't getting scared by sci-fi and fantasy shows, they always had monsters.
Even Firefly had elements of horror - the Reavers.
So, you can't neatly categorize for all shows. What distinquished Buffy from Twilight, Moonlight, Vampire Diaries, True Blood, etc - is that it contained elements of both gothic fantasy and sci-fi, reinventing the vampire genre as a result, creating a new category known as sci-fantasy with urban sci-fantasy. Granted the science isn't always accurate, but that's true of most tv shows. 90% of the science on Caprica, BSG, Star Trek and Doctor Who is far from accurate.