Put me in the "fun in small doses" category. From a world building perspective, they make an otherwise static zone come alive. Each FATE is a tiny mini story, with bits of lore, occasionally interesting characters, and a variety of mechanics. The longer FATE chains can tell a much bigger story, almost an open world quest series of sorts. (The one in the steppes with the tribe that marries their horses was fantastic.)

I don't mind doing them for occasional events, but I also intensely dislike grinding them as a form of leveling. Outside of the Yokai event, I'll do the 10 needed to get my weekly challenge, and then go do something else.