I have so many questions about evolution

Why do males have nipples but not be able to lactate? Like what possible reason could there be for making sure only half the population can feed infants?

Also, why nose hairs? What are they for, filtering air? Then why don't mouths have them?

Why do we have soft, easily hurt feet if we're supposed to walk barefoot everywhere

@kimdanes Nipples get formed before the body knows if it's gonna be male or female, and just kinda stick around no matter what. Nose hairs catch germs and dirt. Feet are stupid.