AFAIK FFXV had a much better story planned out; but they were pushed to release it half-baked, so they cut out a bunch of content to make it smaller-but-semi-coherent, planning to add all the extra context back in the form of DLC. But then the first DLC didn't sell amazingly well, and the rest just got cancelled :(
(Pretty much the same thing that happened to Deus Ex: Mankind Divided, also by Square Enix...)
I only just played this game last summer/fall (I guess once it showed up for PC). While there were definitely enjoyable aspects and I played through the whole thing, it really did feel like half a game.
I'd played most of the NES/SNES/PS1 entries (some all the way through, some partially before getting sidetracked) and while the stories were often convoluted or just poorly localized, they were lengthy and had a lot to do.
The latest FF game looked great and I could deal with the sketchy plot logic but right around when the pacing suggested that I was getting to the "meat" of the game, it went on rails (in some aspects, literally). I was used to the idea of a long setup with a false sense of conclusion, right before it "hits the fan" and the big bad shows up/you end up in the world of ruin/whatever.
When this game went from the peaceful storyline and fun time world exploration with your buddies to "oh crap wtf shit is going down!" it was followed by a series of simpler missions in a few locations, then the end.
I don't even care that the ending itself made little sense unless you had watched some movie or whatever. I was mostly just bummed that the exploration, discovery, dialogue, etc. ended so abruptly so you could fast track to the inevitable showdown with the big bad (who was disappointingly the guy you were led to expect, not the usual fake-out where he was just a pawn of the real ultimate baddie).
Later I read the same thing about how the game was cut short (which also explained all of the locations marked on the map
that you couldn't actually visit). Made total sense.
It's a shame they put it out like this. As I said, I only played the PC version which came out two years after the initial release but I would've loved it if they just waited until 2018 and put out the full product. I hadn't played one of these since maybe FFX in 2002 so it was kind of a bummer.
The latest one is just garbage, story-wise despite being absolutely beautiful.