Ahem.
Given that the preceding discussion has largely taken place in (or at least largely alluded to) a judeo-christian paradigm, I feel compelled to step in as E2's taoist chaplain and provide an alternate viewpoint.

Thus:

Dominance and Submission are obviously aspects of Tao. The Yang is dominant, the Yin is submissive. In order for a relationship (or a society for that matter) to be in balance, there must be a dominant half and a submissive half. If, in a relationship, there is a dominant partner and a submissive partner, this is hardly abnormal. It is, in fact, super-normal. The couple has become a perfect expression of balance. Rather than condemn such people and their practices, we should applaud them for attaining such perfection.

FMGPD