What's wrong with modern fantasy settings?
XII and XIV are more "traditional" FF fantasy. XIII and XV are FFVII-esque sci-fi/fantasy. SE isn't giving us the same thing over and over again and people are complaining about it.
XIV was created with no originality whatsoever. Yoshi P designed the game so he could gather up as many World of Warcraft players as he possibly could.
I personally thought XII was poorly designed and had some of the worst characters in the entire series. I just couldn't get in to the characters at all.
The last good main series Final Fantasy was XI and that was the best MMO of its time.
Edit: Oops, forgot to actually answer your question, sorry. I just don't care for science fiction games or any science fiction stories at all for that matter. They just seem so boring to me. I feel like there's a lot more room for originality and interesting ideas with medieval or steamplunk settings that haven't been done yet. Most science fiction games are just too ridiculous with their designs. I would say that the previous medieval Final Fantasy games are more "realistic" than the Final Fantasy games we get now...