Yeah, half the pretension is in the level of belief invested in it. (The other half's in the level of belief they've invested in its not being horoscopes.)

I really don't get the "Sorting characters for the sake of it" thing, either! For a fic, sure, but I can't quite grasp the point otherwise, except as a five-minute entertainment when sitting on the train or something. I can't imagine trying to use it as a ~deep insight~ into a character! :P Anything that can be summarised by a singing hat is probably not that deep.