Fair enough, but by no means are they the only women in art. In fact, one woman has dominated the Western art scene for well over a thousand years -- the virgin Mary.* I'm not Catholic, but I'm guessing none of these artists imagined Mary looked like the toothless crone down the street. So the question isn't "Is this woman supposed to be pretty?" but rather "What sort of pretty is she?" Encapsulated in these images is the girl next door, ethereal beauty, and probably images of the artists' wives and mothers.
Again I'll say, worrying about the prettiness of your features is like trying to make everyone like yellow. It's just opinion. See our Concepts of Beauty in Art gallery on Facebook for more examples.
*You should read My Name Is Asher Lev by Chaim Potok. It's about a Hasidic Jewish boy learning to paint, and his studies of art history lead him to images of Mary and Jesus. It's a beautiful book about art and family.