FFXII is a good game with a good story but this is something that holds true for every Final Fantasy with the notable exception of VII. VII features the Slums and gave them quite a prominent position in the story. Shinra's ruthless exploitation is a consistent theme throughout Disk 1 at least.

Then, in XII, we have the royal capital and this place underground where all the undesirables of society gather. Old men and insurgents and bandits and failed merchants congregate. It is dark and bleak and this is the music they went for.

Old Archades is a bit "better" but it still features dancing moogles and a pretty whimsical sidequest with equally whimsical music.

Why don't FFs deal with this kind of systemic oppression and hopelessness more often? Not the kind forced on people by a evil god that you can just whack and make go away but something far more insidious?