You know, I would've described Heinlein or Asimov the same way - people using slide rules on spaceships and so on. However, I happened to go back and read a short story and realized that it did in fact present a very plausible space age about 20 or 30 years ahead of time, and it's kind of uncharitable to criticize it for not accurately predicting 50 or 60 years in the future.
Sometimes we look back at, say, the 40s and the 70s and kind of lump them together as being long ago, but predicting a lot of things about the late 60s or early 70s from the perspective of WWII or its aftermath was really an achievement. Of course, as always, a lot of the reason for successful predictions was that the people who constructed the future had read the predictions for inspiration.
Sometimes we look back at, say, the 40s and the 70s and kind of lump them together as being long ago, but predicting a lot of things about the late 60s or early 70s from the perspective of WWII or its aftermath was really an achievement. Of course, as always, a lot of the reason for successful predictions was that the people who constructed the future had read the predictions for inspiration.