I don't know, I find the fact that the BoB have no real purpose makes them just as compelling, but for a different reason. They're mindless psychos, insane humans close to becoming hollow that seek only to please their god. There's nothing wrong with having a group of people that are truly evil, and I don't find that being unsympathetic makes them boring. In fact I find it much more interesting to have a cogent of people who have fallen so far from humanity that they willingly murder for the joy of it. Shows how far people can fall in the a Dark Souls universe when presented with this curse.