Well I think you're just putting more weight on a trailer than I am. They don't tend to tell you that much about the final product really, except some of the general concepts and themes. Can't you remember that original FF13 trailer that looked incredible, where it made it look like the battle system was almost like a cinematic cutscene (which of course didn't exist in the final game at all, because that would be a nightmare to design for an entire game):

https://www.youtube.com/watch?v=B7uwtFpC4iI

Or that original FFXV trailer, where pretty much 100% of what was shown ended up being cut from the final game:

https://www.youtube.com/watch?v=IcUSXub_ypU

This is probably not the kind of setting and style I would've gone for either. Personally I'd like to see them retry something like the FF13 sci-fi aesthetic, but with a better implementation. But I don't think all of that stuff matters too much at the end of the day. The quality of the game will ultimately come down to its story, characters, gameplay, and world design. Not its surface level aesthetics and themes.