I don't agree with this. Many writers in the 80s would still have been too young to remember WW2 (some might have even been born after it entirely) and there a

I don't agree with this. Many writers in the 80s would still have been too young to remember WW2 (some might have even been born after it entirely) and there are still plenty of sci-fi stories and scripts being written which are based in the future. I think the explanation is a simpler one: writers didn't know any better. In the 50s through to 80s exaggerated predictions were made based on observations of the way tech was advancing at that time (much of that kind of tech was new). However after people grew up and realised those predictions were vastly over optimistic they would then go on to set their science fiction stories at a more pragmatic date in the future. Sometimes writers these days don't even specify a date and I suspect that's intentional to avoid jokes about it's "predictions". Simply put: Writers these days are just more aware of how quickly dates change and how long their content remains in the cultural conciousness. It's also worth baring in mind that a lot of the time these kinds of stories are "alt universe" type stuff. ie based on some theoretically similar universe to ours as well as x number of years in the future.