That's not really an answer at the "why", more a claim that "yes there is such a need". But I wonder. Normal human interaction also involves eye contact, gestures, a lot of things we do without on-line. I don't see why gender identification is different.

Maybe it's language. You can't say "he/she" in an asexual way in English. In Hungarian, it's just the opposite.

_{*Lunatic*, n.
One whose delusions are out of fashion.}