I think anyone could have told you this. AC0 released after FF15 is the one of the latest releases in an open world IP, but a publisher who specialises in open world.
I dont think the troubled development FF15 is an indication of anything relating to the open world for the next FF.
I took into account the development history, but the game still has elements that feel backwards or against the concept of an open world game. It feels like the ideas were naturally just outdated.
As much as I hate FFXV from the bottom of my heart it's not really a good comparison. FFXV is going for a complete different experience than ACO or other western open world games. The open world isn't even an actual open world. It's just a series of large areas as it is done in all large scale JRPG. In fact I have yet to see the first open world JRPG. The thing is, do we even need it? The west has already perfected open world games so it's nice to still have your regular JRPGs. Going into a JRPG and expecting ACO or the Witcher is like going into a JPOP concert and expecting Finnish Hard Rock.
I actually forgot to write in the OP that FFXV feels less open world and more like if the Calm Lands were the entire game. SE has made it clear that they intend to continue the open world and quite frankly bro, that opens the door to be compared to other open world games even if they're not directly trying to a western style open world. With that being said, I'm on the opposite side, they should redesign a Final Fantasy that fully commits to an open world if they plan to continue on that path. I love XV but it so half assed.
Please I don't want FF to become AC.........
To be clear: I am not saying that Final Fantasy should be more like AC. NO! I am saying that open world Final fantasy needs to understand what makes an open world tick because FFXV was open world in the most simplest form.
AC O and FF XV are completly different games that try to do completly different things. And ACO isn't even one of the best open worlds, its standard AC open world, lots of uninteresting things to do everywhere and some nice vistas. Anyway FF shouldn't try to be open world at all, it should go back to being more linear, maybe take a leaf from Persona 5's success and stick to your guns, we don't need every game to be open world.
Final Fantasy is Global brand and one of the premiere Japanese IP's that is intended to represent the highest quality work from the country. It is not some B class JRPG. Where P5 is at Final Fantasy has been there done that a loooooong time ago. Up until recently, Final Fantasy has always been a leader that set the bar for Japanese RPG's and Japanese gaming in general. SE should never turn Final Fantasy away from that role because that pressure is what makes Final Fantasy the beloved series that it is. Your idea is simply run away.