The joy of being a top or dominant
When people consider BDSM, they often see two things:
- That there's one person receiving a lot of stimulation from their partner, and
- That it seems to mostly be one way.
Tops, dominants and masters aren't necessarily well-known for their philanthropy and so the question arises: what do they get out of it? If they're doing all the work with the ropes, floggers, candles and so on, how can they find it as rewarding as their partner who is tripping out on orgasms and subspace?
Part of the answer is that the top, dominant, etc., gets to feel that they have power over both their bottom or submissive and what their bottom/submissive feels and experiences. Control and power are possibly the most common motivations for many of the activities BDSM practitioners engage in and so using rope to control or limit your submissive's ability to move, or to use floggers or whips to inflict pain on them and provoke feelings and reactions are both immediate and direct ways to exert that power or control.
At the same time, the bottom or submissive is also directly feeling controlled and this is also a common motivation for BDSM.
Penetration has to do with being affected by your partner. In the case of a top or dominant, as his submissive partner responds he will also likely respond. If she is becoming sexually aroused then he will likely become sexually aroused. If she become passionate or excited, he will become passionate or excited. This tends to be self-reinforcing cycle with the submissive reacting to what her dominant does to her, then her dominant reacting and growing more excited due to her reactions, then his increased intensity turns her on even more, and so on.
AS a consequence, one of the most challenging types of BDSM partner---be they submissive or dominant---is one who either doesn't react or who doesn't show their reactions. This breaks the cycle I mentioned in the previous paragraph and means that there are no displayed feeling or reactions for their partner to feed from. It severely limits the intensity to which a scene can rise.
Penetration is also significant in the service nature of dominance and submission. In service---whether it is the submissive serving the dominant, such as by serving food or drinks, or by providing sexual service; or whether it is the dominant serving the submissive, such as by satisfying the submissive's desire for subspace, pain or bondage---one of the key elements is that the service actually affects the person being served (i.e., penetrates them), and that the person providing the service gets some form of acknowledgement (i.e., is penetrated in return).