Why? Evolution probably. Women select desirable characteristics in a sexual partner and a provider/protector (not always the same person.) They weed out undesirable qualities to avoid creating and having to live with inferior offspring or an inferior home environment. Women are selective because women have more to lose if they make a bad selection.

As the pace of technological and intellectual progress outstrips evolution, these inborn drives become more an more irrelevant despite their continued influence on us. Although we need not live our lives according to the default programming, many still choose to do just that, not realizing that their choice is more the product of instinct than of rational deliberation. Our species is stuck in transition: No longer animal, but not fully human. Half a goon, and half a god.