I'm really not convinced that this is true. We know that in EA you had a scene where you felt a sudden urge to kill Daisy, but that's it, nothing else even resembling that in all of EA. So clearly if Dark urge was on their radar it was nothing more than a maybe cool idea, nothing as cut and dry as "original jntended PC." And if that were true, then my guess is Larian separated them so that they could go full on edgelord, gory crazy stuff now that they had an option for players who didn't want that.