In Jane Austen's novel, Pride and Prejudice, Elizabeth's attitude about women settling for less than they deserve is a strong theme in the story. However, she is also concerned about how a woman will show no compunction whatsoever about "taking out" her competition by "undervaluing" the female sex in general (which ironically may spell disaster for the scheming woman in question anyway).
Elizabeth is very unhappy when her friend Charlotte accepts the proposal of Mr. Collins, knowing that her friend does not love the man. Charlotte represents a woman in Austen's society that was not always fortunate enough to wait for a marriage based on love, but on convenience, as a woman's choices were limited: without a family or husband, a woman had few acceptable career choices, and faced a lifetime of drudgery and want. Charlotte is being practical, but Elizabeth struggles with the concept that this situation exists within her society.
In keeping with Caroline Bingley's attempt to attract Darcy by undervaluing her own sex, this is also something that Elizabeth cannot countenance. Caroline is responsible for driving a wedge between her brother Charles and Jane Bennet, something that eventually comes to naught. In trying to condemn Elizabeth in Darcy's eyes, Caroline is responsible more for undervaluing women in general: besides being a snob, she places too much importance on one's appearance, discounting the value of the woman beneath her beauty or lack thereof.
Ironically, this behavior backfires, as Darcy resists Caroline's attempt to dissuade him from his attraction to Elizabeth; if anything, he is more determined to have her.
Austen, in speaking through Elizabeth, shows the reader that here, once again, is another kind of woman within England's society, who though she may be motivated by love (which Elizabeth would admire), is willing to demean the personage of another woman who presents any competition.