I've read one or 2 convincing essays that SW is basically fantasy rather than science fiction. You have princesses getting rescued, and 'magicians', etc.
When you start analysing it, that basically holds. Sci fi should be about holding up a mirror to contemporary issues, or imagine what may be. I suppose the hard/soft difference is how rigorously they think about the mechanics of that, but theres a big grey area in there. I supposes theres an element of no true Scotsman in there, but these aren't hard and fast rules.
To return to my original comment, I don't think there was ever an attempt to predict, or realistically portray anything. TNG I would expect to at least check up on the state of the art was at any particular time. If data uttered something about doing the kessel run in 12 parsecs, I would expect that to be in the context of a thought out space folding drive. I'm still not saying that ST is 'hard' Sci fi, as the multitude of things that happen as you approach warp 10, or the many ways to travel back in time evidence.
Star Trek is "Wagon Trail" in space. Star Wars is, I think, space opera. The Expanse gives a nod to hard science, and I respect them for trying, but e.g. the gravity is always either 1 or 0 g. i'm not complaining, I think realistic sci-fi would be kind of boring. Like the first half of "2001: A Space Odyssey", it was basically Dr. Heywood taking a plane. A freaking awesome plane to space, but still.
I have a "100 Sci-Fi Movies" DVD set with lots of old movies from a span of decades, and it's pretty clear that at least some sci-fi did start as attempts to do a kind of scenario planning, but there has always been "speculative fiction" depending on how you categorize things. Was Plato's Atlantis science fiction?
In the Expanse TV show yes, it seems that way. However I suspect that is more due to keeping production costs down. In the books, gravity varies all over the place depending on what moon/planet/rock/station the characters are on, and even goes into details describing the differences of spin gravity near the center of a station vs outward.
At one point they use CGI to show off Coriolis force on the asteroid, and I took that to be a kind of message from the show, "We know about this stuff but it's too expensive to do all day every day, so here's some science "fan service"." Like I said, I respect them for it. :-)
Regardless it's a pretty cool series :)