In VIIR when you get to an interesting looking area you can take a minute to have a look around and take it in, it's not deep exploration but you can take it in and see the world for what it is.

In XIII when you get to an interesting area (Like a theme park) and you want to have a look around and explo...."FUCK OFF CRYSTAIDS!!!"

The issue isn't linearity, it's that they chose a narrative that just shoves you through it all. Hell X is one big hallway but it's not rushing you through everything, you're taking your time in what is stated to be a long journey.

XIII gives you one area in the whole game to slow down, in an area that frankly it's only real interesting aspect is the fact you're not getting shoved through it. You only need to compare guides to all the games to see the issue with XIII, every guide is literally just a list of fights, there's nothing else, in VIIR there's little paths or whatever with something you can pick up in them. As I said it's nothing deep, but it's more than the nothing XIII has.