You're not going all the way with this: if we didn't incessantly pigeonhole ourselves and each other into sexual categories, there could be no systematic discrimination on the basis of the stable sexual categories. (I think I stole this from Joanna. It's come up on the list before.) The "desire for control" requires stable categories--cf. the incessant social concern with the correct racial classification of babies in the deep South during Jim Crow (people were fined and jailed for violating the "one drop" rule). Take away the stable categories, the system of racism (or heterosexism) cannot survive.
Note that this isn't pie in the sky socialist dreaming, either: many societies throughout human history have survived and thrived without anything like our notion of the stable sexual identities "gay" and "straight". As far as I can see, the only thing to be gained by classification of self and others into rigid, discrete sexual categories is an heightened opportunity for discrimination and stigmatization. Yoshie has a "strategic essentialism" argument here, but I don't buy it.
Miles