It's easy to imagine ways the future can be ugly and depressing. It's harder, but more worthwhile, to imagine plausible ways we can make it better.

Of course, the way writers think about those things is almost certain to be affected by their own cultural background, and it would be hard to deny that, for whatever reasons, a lot of SF writers come from Anglo or European backgrounds.

And, of course, some SF is set close enough to here and now that Anglo and European do apply. Since many of the writers come from those backgrounds, so does much of the fiction.

There may be something to the suggestion about the pace of technological change intimidating writers, though - it's been awfully hard to keep ahead of real developments.

This means I must pay close attention to the writing, but equally so to the scientific background - which sometimes means doing fairly involved calculations.

Resist the temptation to try to use dazzling style to conceal weakness of substance.

Its limitations are those of the physical universe: it won't let you play with some really wild ideas that aren't possible, but are fun to speculate about.