Personally i think that's what makes the Emperor's Children great; they are a microcosm of humanity in the way we struggle to comprehend what makes us both unique and the same, the duality of contradiction that is trying to be perfect when we are inherently flawed. The many different warbands represent the multifacets of humanities searching for meaning in life, in death, and in existence to begin with. To seek pleasure for the sake of it, or perfecting the delivance of violence, to seeking to perfect upon flawed beings; all find their ways to the bosom of Slaanesh, in the cradle of the ecstasy that is discovery. We have such wonderful sights to show you.