You have essentially a team sport (yes, there's also the individual component), of course fans are going to be "tribalistic" about their teams. And as any sports fan knows, the team that's been dominant for a long period of time tends to be polarising, you're either with them or against them (especially when that period of dominance started with controversy).
Doesn't mean it's a good look for boos at a formal function as opposed to race day, but can't say this is a surprise.
Probably depends on what parts of FFV you enjoyed really. If the ability to customise every character in your party was the selling point, Final Fantasy X-2 might be worth trying. It also has a job system and characters can change jobs during battle as well.
Final Fantasy XII also had a pretty flexible system where you could assign classes to each character, and then customise the skills they each had. The definitive release of the game which is what you'd be getting if you buy it for a modern console has the ability to change all this out and redo it easily if you don't like the path you've taken.