My Man and I don't consider giving oral sex a "favor" either. We both enjoy giving and receiving it. And we both do frequently.
I think you'll find in this population (Eden) that most hetero women enjoy giving head to men, as much as the hetero guys enjoy giving head to chicks, and the GLBTQ people enjoy giving head to whomever it works out well for them.
We're a pretty oral-friendly group of people, as a whole. (At least with our partners, most of us.) But everyone is a little different.