i don't think the problem is the offence insults do to people.
sex has a great power on the human (animal) mind -war propaganda, advertising etc. is and has been based on sexual concepts,
and sexual identity, whatever it is, is one of the most important things to an individual.
the problem with insults is when they categorize someone, therefore putting him/her virtually out of the "social whole"; doesn't matter if it happens on internet because
everyone feels at least a bit represented by his "avatar" on the net.
In a time like this, with a widespread trash freudian culture that relates and explains everything
through sex and sexual identity, somehow this is also why some -i think younger- people say melee fighting is more courageous, manly
and what not while archers are my old friends, particularly in crpg, where the identification of the player with his own avatar is much easier than in native.
As with racism, the problem is despise for certain fictitious categories, even if it just starts as a joke, becomes a normal thing in time, with possible further developments,
for example in times of economical, social crisis. No ethics are written on stone.
edit: sorry for the long post