>>12537851There has to be holes in order for menstrual discharge to fall out of, just like males have foreskins but these aren't sewn shut in order to allow the male to pee.
They protect sensitive organs from the environment. Are you going to ask what are eyelids for and why to our skulls have holes over our eyes? Or why do our nasal passages possess extra hair and excrete mucous? Or why do our ears excrete earwax?
Its all for protecting the sensitive openings of the body.