Let me play devil's advocate. If there were two guys and two gals tossing a ball around, saying, "He threw it to her." would be just as ambiguous as "He threw it to him.". So introducing a binary distinction only helps so much. "The tall one threw it to the short one." Maybe in very small groups it serves well, but once it's applied to large numbers, it can as easily be misleading, as useful. There is a dimorphism between men and women statistically, but the overlap is actually quite large. If you have four men and four women, and you want help lifting something, saying, "He who can help, please step forward." might mean missing out on the strongest, a woman.
The pendulum has swung; not so long ago, the distinction was a means of oppression, but now it is a means for the oppressed to gain recognition and compensation. Will the day come when the male/female check box disappears, and we are all just people among people again? (With the possible exception of the maternity ward!)