You don't send a message if the receiver can't understand it. People need to have a point of contact with that extrapolated future to became a popular science

You don't send a message if the receiver can't understand it. People need to have a point of contact with that extrapolated future to became a popular science fiction work, even the culture in the far future fiction is usually pretty similar to our own (or at least, the one of the moment where that book was written). Present works (not the ones with inherited universes from old ones) are updated to our current expectations of the future, so you have sentient computers and other "possible" technology, and probably in 50 years we will have a different set of standards and not something as naive as what used to stand as possible 50 years before.