The world feels too small in XV. When we finally get to the other continent where it's supposed to make us feel really far from the beginning of the game the devs just butchered it thanks to deadlines.
I mean I don't disagree that the Imperial Continent being delivered the way it was was a mistake, especially when they DID model as much of it as they did. But XII similarly feels like a tiny piece of a world. It has "more" locations nominally, but virtually none of them are interesting or have anything to do in them.
X was the beginning of the scale crunch that's hit Final Fantasy as hard as it has, and XII was another victim of that. Ever since we lost world maps, the series has felt less and less like world-spanning adventures and more like a bunch of lego playsets assembled in a tiny backyard.
Oh XIII-2 is a scream in its entirety, the fact that they thought that the best way to make a continuation to the first game was to make the main character literally fall through a spontaneous crack in the ground seconds after the climactic self-serious ending of XIII will never not make me laugh.
Lightning Returns is no slouch in the hoot department either. I have a theory that it started as an unrelated lower budget game that they just grafted the tangled XIII mess on top of. I actually really like it on the gameplay side, there's a lot of unconventional shit going on with the mechanics and story structure and I think it would've attained a bit of a cult status by now if it wasn't for its ties to the desecrated dark horse of the franchise. As it is, it's just fucking bizzare. Truly one of the most baffling trilogies in gaming.
Lightning Returns is pretty much at least partially built off of the skeleton of a Valkyrie Profile game that didn't get made, along with some cut Versus XIII art assets.