I think the big hit to the series was voice acting. When it's read, it's fine. When it's voiced, Final Fantasy's need to be esoteric filled with game specific lore jargon makes it sound like a bunch of nonsense. A lot of people complain about JRPG writing as anime-y, I don't think Final Fantasy games writing would make it to production for an anime that had to stand on its own merit, no FF association. Feel like FF writing quality is somewhere around Fist of the North Star but not as endearing wheras modern shounen anime is post-Yu Yu Hakusho where its not just mature themes but where it reads like the author really believes in what they're writing rather than thematic checklist writing by a collection of writers and producers

The Sakuguchi games I think balanced the edgy grim dark "Final Fantasy" apocalypse stories with some lighter moments that give the world and characters more well rounded characters. I think that's the magic. It's apocalyptic but there's a sense of hope and magic and perseverance in the writing and art