I think XIII had a better developed cast, but I also think that they were pretty poorly written and mostly over dramatic. I liked that VIII's supporting protagonists didn't really take themselves too seriously and provided some good comedic moments. They were mostly static characters outside of Squall and Rinoa, but I also never really felt they needed to be different people by the end. I also find it hard to be bothered in this instance of "Why are these people together throughout the game" because I think it's fairly easy to explain. They were schoolmates that ended up being put on the same mercenary team. There isn't more to it than that and there doesn't NEED to be more than that for most of the game. A good chunk of the game is them working on their missions together, and this ends up all going wrong for them. It diverges from that point, but they work together to make it back to Garden and to protect it. Once they've all made it back to Garden, it can be questionable on why all of the side people are still there, but by that point they are probably comfortable as a team and have built a bit of a friendship. You also have the reveal of being childhood friends which I'm sure they'd want to explore.

I'm not saying these are all fantastically written parts or anything, but I just think the characters being there for most of the game is consistent with what the game presents you. I also enjoy the characters better despite acknowledging that the protagonists of XIII are better developed (but not better written). VIII's villains are way better though. It's world is way better as well. I also think that despite it's issues that it's story is told way better (and Laguna's story is better than either XIII or VIII's main story). Also the way VIII's story and world is laid out with a lot of it's weird aspects, it becomes open to a lot of interesting interpretations and analysis. I don't care if Squall is Dead as a theory isn't "canon;" I think it's just as valid of an interpretation as taking the story at face value or any of the other interesting theories out there. This comes from looking at it in the same kind of lens that scholars use to interpret literature. XIII really doesn't do much of that until you start bringing in the sequels.

I also think that saying VIII's gameplay is broken isn't very accurate. Broken gameplay is not the same as having the ability to break the game if you choose. I can accept the criticism that all of the characters are the same outside of their Limit Breaks, but what this game gives you is full customization of your characters. You could make your characters to be different if you wish, but there is no real reason to outside of maybe creating your own challenges. You could stay level 1ish and just boost all of your stats to make the game easy. You could level up to 100 and keep all of your stats low to create more of a challenge. You can break it or you can make your life a living hell while playing or do something in between. I just can't accept the idea that this game is broken because it take away grinding for levels and just moves that grinding to grinding for spells to junction. It's not really any more broken than any other FF game I feel. This part just depends on what your looking for from the gameplay. I can see why you wouldn't like it, but I like it for the same reasons you don't like it. Outside of the battling mechanics, you also have a world to explore in VIII, and I never felt like what I was doing was pointless like the battles in XIII at the beginning where you can't even level up or anything for a few hours.XIII was just too closed off in nearly every aspect for way too long.