1.
Because the words "female" and "woman" mean different things.
2.
Because reducing a woman to her reproductive abilities is dehumanizing and exclusionary.
3.
Because nobody casually refers to men as "males."
4.
Because it is most often used to imply inferiority or contempt.
5.
Because it's grammatically weird.
6.
And most importantly, because the word you're looking for already exists.