Several years back, I somehow ended up at the first ever meeting of the Indian Association for Science Fiction, an organisation which may or may not be defunct by now, and one of the 'big shots' there was this telegu writer of SF. Since he was one of the few there who actually wrote science fiction, he was getting a lot of attention. But his most annoying repetitive contribution to the discussion was the take that SF is *supposed* to predict the future. And I found that this view is quite prevalent, i.e., that SF is just another term for Futurology. Bring up anything and he'd go on and on about how it was all mentioned in the Vedas, and that the Ancient Indians thought of everything first. The real point of SF, as JP says, is that it gives us an opportunity to hold up a mirror to reality, but not so much an objective one, but rather a distorted one, with the irregularities in the image a product of the writer's particular point of view.
I think that the genre of SF really comes into its own when writers attempt to show a world not so different from ours in the grand scale of things, but very different from ours where it counts. Just a small tweak in a social custom and you can have entirely unpredictable and fascinating consequences. To use a bad analogy, it's a bit like exaggerating to make a point.