Alternative hypothesis: something set 21,000 years (edited - well spotted!) into the future is going to be as impossible to imagine for us as today's world was for Jules Vernes. As such gothic madness might be a more realistic interpretation.

A lot of the criticism misses the mark. I can try and find alternative explanations. The "outdated" computers? The Butlerian Jihad caused that future world not to build anything more complicated than a light switch. The unique worlds, monochromatic and with their odd uniqueness? Visible signalling of these being different cultures that survived by virtue of their unique characteristics. Unlike the "bugs vs Marines" of a lot of space opera, the Tleilaxu, Guild, Bene Gesserit and Harkonnen are all fundamentally different, their differences giving them a survival edge, influence and power. Black desert suits? Maybe the filters need solar energy to run. Erotic Bene Gesserit intonation? Have you read the later books?

This was the only depiction of Baron Harkonnen which I thought truly captured his sadistic genius. And the blocky shields are so much cooler than the form fitting transparent bubbles of later Hollywood SF (e.g. Star Wars), also explaining the difficulty involved in going slow for so long when trying to penetrate them (because the space between shield and human is so great). Or what about the worms, which despite (or perhaps because of) the sorry state of 1984 CGI somehow were just as immense as I had imagined them reading the words. There was this alien feel to all the vehicles, especially the ornithopters and the harvester carrier, which has only been recently replicated in the seemingly nonsensical vertical ovals of Arrival or the glaring contrast between earth and ship in District 9. This was definitely the artistic generation responsible for Brutalist architecture, which is not always fun to live in, but has a thousand times more soul than the International Style condos copy/pasted across all of the world's megacities today.

Lynch's movie was glorious precisely because it freed itself from the constraint of present day science and became a standalone creation from the inspiration of the source material. The other interpretations did not create that sense of awe. I found the miniseries particularly boring, a kind of BBC period drama feel instead of being transported into a completely new, intense world. What makes Dune great as a book and as a 1984 movie is precisely that it frees itself from "realism" and suspends disbelief in just the right way for telling a great story. Might as well complain about X-wings flying like F-14s and making sound in vacuum...