Final Fantasy hasn't been great since FF10. One could say the FF game that HAD to be great was FF13, and it wasn't, and it still sold fine.
Not sure why being Japanese makes it a sub-genre either, it is still just a regular console RPG, and those are made all over the world, just mostly in Japan. Console RPGs also sell a lot more than all other RPGs combined.
That said, FF15 isn't even really an RPG, it's an action adventure.
I describe myself as a little dose of toxic masculinity.







