Some people may not feel like gender makes such a difference in how they relate to others. This doesn't back the idea that erasing differences is a desirable thing, but it probably lessens the extent to which the fact that humanity has two sexes adds to life's interest

This basically sums up my thoughts on the matter.

Either gender differences are intrinsic sex differences viewed through cultural lens, in which case erasing the differences isn't possible anyways baring advanced technology; or they're pure socially constructed groups with sex-biased membership in which case the proposition that gender is more relevant than any other social group identity strikes me as weakly defended at best.