I’m not very well-read so my opinion comes from a select well-known big hit novels/series, but mostly film/tv and also a vague, surface-level knowledge and understanding of themes, settings, etc of some of the important works I haven’t read

IMO a lot of earlier scifi was conceiving of possibilities or coming up with weird ideas and building a world and narrative around them, and sometimes you can’t make a reasonable way for this to occur from where we are in our reality. So you do “a galaxy far far away” or 10,191 or something so far out that earth is a long-forgotten planet, and now you are doing something more similar to high fantasy world building, and can do whatever you want.

Versus a later generation of sci-fi stories that are cautionary tales about things that could become invented, and how they would integrate and affect our current societies over a (relatively) small number of years.

I’m on my phone so I don’t want to completely rewrite what I just wrote, but I do want to clarify/correct that this is not actually “earlier” vs “later” - there are examples of both all throughout scifi history - but perhaps what has entered the mainstream via adaptations, smash hits, cult classic, etc. pathways. Basically it depends if the author is writing a cautionary tale or metaphor, developing a conceptual & epic universe, telling an allegorical story, or whatever else - and then oftentimes popculture dictates which ones people become familiar with.

Anyway it’s super early and as I said I’m on my phone, so I hope these thoughts are coherent and at least vaguely interesting to you. I found your question thought provoking and wanted to respond. Cheers