"If we were to snatch the screen-writers out-of-time, they'd be surprised that the world has changed so little."
I'm not sure about that. It's just that the things they imagined are not the same things that have changed. They thought we'd still use Fax-machines and their idea of our video communication and display technology was ludicrously pessimistic. The reality is that they picked funny and visually entertaining ideas of progress. I doubt any of them thought we'd actually have re-hydrated pizza the way it appears in the film, it was just a funny idea that would give the viewers a laugh.
Instead of these ideas we have the WWW, Smartphones, insanely pixel-dense displays, wifi, Viagra, etc. The Internet, while it existed in some form as "Arpanet", was nothing like what it is today and the script writers, if they had even heard about it, surely would not have thought about it much more than as a research tool, as evident by their use of fax machines.