[mogrim]

It's amusing to try turning it round, makes you realise just quite how sexist it actually is:

"No, of course I'm not offended by being called a firewoman, why would I be? It's clearly referring to both women and men" - Jake Miller, Firewoman, Springfield Fire Department

[saberience]

You would probably feel differently if you had learned the term man and mankind also refer to all human beings and that usage had been normal and active for your entire life.

Of course saying womankind sounds funny now because we haven’t heard it used for our whole lives. The term mankind derives from Sanskrit meaning children of Manu (a god). It’s not a sexist term and we’ve gone 2000 years without people finding it offensive, it’s only one that people with no other issues in their life need something to be offended about and decide to make a war on words.

[tsimionescu]

The words woman/women refer explicitly to a group where every single member is a woman (female).

The words man/men, at least historically, can refer either to a group of unknown composition OR to a group where every member is a man (male). Basically it is a homonym with two separate meanings, just like mouse (animal or input device) or chair (object or leader of a committee).

Point being, policeman being ambiguous doesn't mean that we would expect policewoman to be considered ambiguous as well, since woman is not a homonym.