Is sci-fi a real genre at all, or just a theme/setting?
Star Wars = peasant becomes knight, fights evil king yada yada, i.e. a fairytale
Firefly = character-based action series
The new Battlestar Galactica = character drama mostly?
Gattaca = essentially a parable about genetics
H2G2 = a comedy
So basically all these "sci-fi" things are all super different, each using the "sciencey" contrivances for other purposes.
Sci-fi is what we say is sci-fi, really. So in the end, who cares.