BDSM Tourguide, I agree. We have had some great and thought-provoking discussions on this site, but in the end, even though the idea infuriates some, the submissive is always actually in control, because otherwise all you have is abuse.
Individually we are suited for a particular role, whatever that is, but what is our incentive to surrender our idea about that role is, and submit to another person's ideas about how we might be useful to them, without any compensating personal satisfaction in our own terms? This is a difficult and complex issue, but it is at the heart of who and what we are.
Most people want a relationship to go some way towards indulging their own personal fantasies. That would really work. Indulging another person's fantasies without that compensation is not the same thing at all.
If you really love a woman, what turns you on more than anything is doing what turns her on. Any amount of 'what's in this for me' can never match up to the awesome success of pleasing her. Whether she wants pain, pleasure or just to be pregnant doesn't matter. It's all in there somewhere.
So really, both partners need to be unselfish in pleasing the other, or they fail to achieve the ultimate compensation for that sacrifice.