I think the rising and falling popularity of areas like hard SF and far-future SF is, to a considerable extent, the same as any other fashion.

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.

It's most presumptuous to believe we already know all the answers and will never get any more big surprises.

intricately and intriguingly woven, lots of fun, and extremely thought provoking.

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.

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.