Asimov on Science Fiction
Actually, science fiction is committed neither to marvels nor to disasters. It deals with possible situations. It tries to draw a rational and self-consistent society, different from ours, which may be better, even much better, than our society; or worse, even much worse; or better in some respects and worse in others. The point of the story, then, is how people live and react in such societies.
Naturally, trouble makes for greater drama than does happiness, and it asks more in the way of human response. Therefore, science fiction (like all forms of literature) is more likely to deal with discomfort than with comfort. Furthermore, it must be granted that given the direction in which our society is now moving, we seem much more likely to end in the soup than to be swimming in the cream.
( From the introduction for Octavia E. Butler's story Speech Sounds)