Because it honestly only does for a short while. You aren't in anything even close to Gran Pulse after chapter 11. And during chapter 11, you quickly begin to venture in linear corridors again. Gran Pulse, in itself, is pretty open, but once you get back on track with the story, it is just as linear. And chapters 12 and 13 don't even come close to being "open."

I think saying the game becomes more "open" is a massive overstatement because you'll still be running down really cramped areas from start to finish, aside from the one instance when the game "opens up." It's like running down the same path over and over again, but with a different backdrop.

I'm just wondering if anyone else found these claims to be a bit misleading.