That was the only Final Fantasy I actually liked. Granted the first sequel was pretty lame and I didn't play the second one, but XIII itself was quite enjoyable to me. There are a lot of people out there who want to play Final Fantasy JUST to see the gorgeous cutscenes and have the story play out. I'm one of them. So I quite liked the linear structure and I'm happy that XV culminates in a similar experience. Considering the gameplay isn't a big draw to a big chunk of the gaming populace (just compare RPG numbers to shooters, sports titles, and casual fare like rhythm games or party titles), focusing it isn't a bad thing. I think they realize that and that's why they went with an action-style combat system this time.
I'm sorry to hear that. XD
Jokes aside, I enjoyed XIII at the time too. It was a good game (there's no really bad AAA game) but imo not a good Final Fantasy. It was after XIII-2 released and then Lightning Returns that I and many fans thought:
WTF are they doing?! Are they mocking us to drag out the series/universe most FF fans just didn't click with? That fact made me and many others look back in such an unfavorable way at the XIII series. If there would have been just XIII I would have looked back much more favorable on it as some unique, quirky, experimental mainline FF.
Tabata did by the way some backpedaling regarding the linear structure of FFXV in it's latter half. It's not the latter half but towards the end of the second half that the focus will shift from an open world experience to the story. There will be some sort of train ride that brings the characters from location to location and story point to story point. So about 2/3 of the game will still be open, phew! And apparently you will still be able to go back to the open-world parts if you want to.
http://www.novacrystallis.com/2016/09/tabata-on-final-fantasy-xv-open-world-and-linear-progression/
I can live with a structure like that. It's similar to how Xenoblade Chronicles (the original) did it to give the story more impact and the player more drive to actually finish the game and not drag it out forever with side questing until you completely burn out. (I never finished Skyrim and GTAV for that reason.) After all you could still do that all after the ending. FFXV seems to handle it the same there. After the ending you will be able to uncover even more of the world.