There is a certain biological
basis to having 2 sex
es. Since sex is genetically determined
, this gives substantial support to having the 2 categories female
Regarding other genders, the situation grows more interesting. This is because gender is a fuzzier concept, and people can be a lot more flexible with it. So an important question when enlarging the gender categories would be "what good is it?". If such an enlargement leads to interesting discussions in sociology, culture, art, history, anthropology or what-have-you, then it surely has some merit, in that it allows us to understand ourselves better. But if the enlargement is done purely to put a scientific façade on the social sciences and the humanities, while furthering the proposer's agenda (whether academic, political or personal), then it is of no use.
Lacking distinctive examples of masculine heterosexual female culture/art/whatever (as distinct from androgenous bisexual male culture/art/whatever, or any of the other categories), it's hard to see what these infinite subdivisions buy us. (I'm not saying they buy us nothing!) And the use of femme as an antonym for masculine above is suspicious: why isn't the traditional antonym (feminine) being used? Surely a good categorisation uses as unambiguous terms as is feasible.
The burden of proof for the usefulness of a finer-grained categorisation is always on the proposer. For example, physics does not give different laws for red bodies than for blue, although this would surely allow more things to be said (red objects might not fall any faster than blue, but they're definitely prettier!). The reason is that such a distinction would not allow physics to say more than it does today.