There's an effect I forget the name of. Basically, if you give someone something and then some time later take it away they experience anger.
When you give rights to one group, you have to remove them from another (important: even if the second group had rights that were not rightfully theirs).
Men previously and incorrectly had exclusive access to jobs (and votes, and so forth). By giving women fair chance to those rights, you have to subtract the unjust portion of men's rights. I don't know why some (most? unlikely) of us can accept the truth, that those rights were never only ours, but as for the rest they experience anger. Just another way that equality is a hard fight: we're fighting a documented psychological effect.