Soft magic has its time and place. By its nature, it's more prone to be mystical - not based on hard facts but on spirituality, feelings, emotions, or higher powers. It worked well in things like Star Wars and LotR, where those stories are intended to feel more like folk legends or fairy tales. And it's the reason why so many people hate the whole midi-chlorian thing, because a hard limit like that takes away some of the mysticism that so many people loved about that world.
It works well in FFXIV, imo. The thing with MMORPG is that it's tricky to set anything in stone. Things are being changed and adjusted constantly, not to mention that your story is taking place over years rather than being told in a game that can be finished in 14 hours. You need to have flexibility with your story, your battle mechanics, your fights, etc. You want your characters to have room to keep getting stronger and stronger and have cool new things they can do as they level up. Soft magic is very friendly to this.
Not to mention the fact that it has definitely given the story a more folktale feel to it than say FF7, which also works well to me. The whole story is your WoL's journey to becoming a hero to the world - it's your folk legend that is being told. I don't think hard magic would let them tell that story as well.
