They got away from what people wanted and too often get mired in dev hell. Tight focus and timelines. No one wants to read three books, watch a manga and play a bunch of web games to get the complete plot of a game. Also turning every game in the series into Devil May Cry is going to piss off fans. It worked (barely) with FF7R but what I've seen of FF16 looks like an annoying departure. People play Final Fantasy games for the characters, the party systems and the escapism. Dragon Quest 11 leaned into all of it's old systems and was a massive success. There's no reason FF has to keep reinventing itself every iteration. People want a role playing game, they can get their action game fix elsewhere and frankly Square doesn't do action very well anyway.
Playing: Total War: Warhammer 3 Immortal Empires, Elden Ring replay, Into The Breach Advanced Edition
Watching: The Old Man, Arcane, House of the Dragon