Well, let's put this into another perspective. How about when you are going down on a girl and she cums in your mouth? Do you take it as that she's degrating you? Or do you take it as a compliment that she's getting off?
Personally, I think that if she's not willing, then that's because she feels that you are degrating her in some way. If she's OK with it, you can only be assured that she's into you and am willing to do.
Vice versa, if I am doing a girl that I am not into, doing her just for sex - number one, most likely I would not be going down on her, two, I would not be wanting her juices all over me. I think this would hold true also for the girl.
I like doing it, because it shows that she's willing to do it for me. I do get a sense of power trip, yes, I can't deny that. It's nice knowing that she's willing and it shows me her commitment.
Ian