Every facet of pop culture points to vehemently opposing stereotyping, and everyone knows that stereotypes are bad. It simply doesn't make sense. Being straight and being gay suggest staunch definitions. There's no wiggle room. Supposing you've only ever been attracted to one particular gender, these two terms are too suggestive. Gay has certain associations and connotations, as well as straight.
Sexuality is no clear and distinct institution. It's a combination of psychological and biological factors. This suggests that it's a health issue, which is an odd thing to define yourself by. It's like having a social identity for type O blood possessors, which is a very silly concept.
Sexuality is a very suggestive thing in itself. Intimacy generally involves two people at a time. Having a sexual orientation is like an open invitation into one's most private part of life. This idea quite simply disgusts me.
From the ultra-gay to the unflinchingly straight: sexuality presents itself as an attempt to wrangle the unwranglable. It's an effort to gain control over a huge factor in our lives. Social sexuality is something that doesn't have a place in one's life.