Obviously just porting the source material over is bad writing, and nobody could call you out for calling bs on that.

And you're very spot-on, Knights have shields, armor and swords. They ride chocobos. They have a crest, are noble and chivalrous. The whole mind powers/white magic thing is a fuzzy grey area (as in, you tell me which one a real life knight probably wouldn't have had ), and if you want to get super technical, in Final Fantasy they typically wear capes, too.

You can do all of that in a futuristic, modern Final Fantasy setting. Just update the various implements and themes to suggest their modern counterparts.

You know, of all the things I am unhappy with about FFXIII, the design of Lightning's weapon is not one of them. That's a cool weapon. There are even better things you could do with the idea of a futuristic, mechanized sword, made of metal, with a cutting edge of some sort. And we still use armor to this day; it's simply a different kind of armor. There are even new kinds of armor being developed. I imagine something on the midpoint of the scale between the style of armor worn by the character sprite for Cecil, and riot gear.

Also, warriors still serve large ruling bodies, and likely will continue to do so for as long as is necessary. You can do a futuristic (constitutional?) monarchy. That's not an invalid concept, and in fact has been done, just not in Final Fantasy. That's all I'm saying, is that it could be done. Not that it should, or will, or won't, or hasn't been.

And I think it could work, with the right kind of philosophy behind it.

As for magic, well, what's FFVII's thing? FFVIII's excuse? FFX? FFXIII? All of those are somewhat futuristic, yet all seem to have magic apparently well known and widely used.

I don't think it's a bad idea. Just different.