I think we’ve reached the point where great effects are so plentiful and “easy” that they can get out of the way and the writers can actually write a real science fiction story and not just an action movie with aliens or robots. And even a smaller, independent film like Ex Machina can have stunning effects. (Though honestly, the script probably didn’t really need them.)
Ava’s look certainly added to the unsettling feel, but if you were willing to accept a practical makeup effect instead, and stripped out some of the modern references, it could have been made 20 years ago just fine.
And when you do have the big budget, you can get stuff like Interstellar, which, while I didn’t really love it, felt like a Clarke or Asimov novel brought to the screen. Or Inception, which again, I didn’t love, but asked real interesting questions about reality, while having stunning visuals to boot.
That, and with all the technological wonders of the past 50 years or so, science fiction is getting closer to reality. While I know intellectually that humans haven’t been on Mars, while I was watching it, The Martian felt almost as much of a historical fiction piece as Apollo 13 did.
I think it’s just a matter of the time being right in terms of what we can do on the screen, what we can do in real life, and what people are willing to accept and take seriously. (There’s a lot less looking down on scifi as childish than there was 20 or 30 years ago).
(On the other hand, I found Gravity too schmaltzy and hollywood-predictable. Decent movie, and the scene of the initial accident is stunning and harrowing, but all the stuff with her daughter… ugh. I loved the fact that The Martian forewent all that and never gave him a daughter or a wife back home to pine for, and barely mentioned his parents. (if at all… that might have been in the book only.)