Ah, yes, there is an old joke among SF fans that takes the form, “Hey! Where are those flying cars we’ve been promised?” A couple weeks ago, after the main discussion at my book group meeting, a few of us (including a friend who is a literature professor at a major university), discussed this issue of outdated SF. We all agreed that one should try to appreciate such stories on their own terms and/or as historical documents. Some have been overtaken by events, such as C. M. Kornbluth’s Takeoff!, John D. MacDonald’s Ballroom in the Sky, and Eric Frank Russell’s Dreadful Sanctuary, all excellent narratives about the first moonshot that seem now like they occur in an alternate universe. (In a spooky mirroring of reality, Russell’s novel features John J. Armstrong in 1972!)
An even greater handicap, I suppose, are those stories that feature outdated science, such as Asimov’s fun Lucky Starr series of juveniles, or all the stories about a benign Venus or Mars. My advice: pretend they occur somewhere else. The most tragic example of this is Algis Budry’s 1958 novel Who? This profoundly philosophical SF mystery—faithfully made into a fine movie of the same name (aka Robo Man)—hinges on the identification of the protagonist. Sadly, its premise is now entirely outdated by DNA identification.
The most important thing to remember—expressed by Heinlein, Asimov, and other famous SF writers—is that SF does not aim to predict the future, but to play with ideas in an appealing narrative.