Men in the military also have to avoid looking slovenly. Presumably they don't do much with makeup but they certainly work on keeping their bodies trim and their uniforms sharp. Insignia aligned. Shoes polished.
The idea that women might do similar things is now unpalatable?
The fact of the matter is that the Officer's Performance Review is often accompanied by a photograph of that officer in full dress uniform standing next to a flag.
How many points a person gains or loses by their appearance is known only to the reviewers.
But not looking good seems like a poor risk to me.