Please explain and analyze the poem "Barbie Doll" by Marge Piercy.

Marge Piercey's poem "Barbie Doll" is an indictment of the socially constructed values of beauty which are forced upon women from the time that they are young.
In the first stanza of the poem, we are introduced to the female character, the "girlchild," who is provided with stereotypically "feminine" toys which imply her inherited responsibilities as a future mother ("dolls that did pee-pee"), homemaker ("miniature GE stoves and irons"), and debutante presented for the visual consumption of others ("wee lipsticks the color of cherry candy").
While the girl is able to survive this childhood and live into puberty, she is soon cut down by the cruelty of a classmate, who comments on her changing body: "You have a great big nose and fat legs."
This is a deeply ironic moment; although the girl has been pushed toward womanhood for the entirety of her life, she is greeted with objectification and disgust the very moment she arrives there. Despite her many wonderful qualities--her health, intelligence, strength, and appetites--all those who are framing her as an object can see are those physical features which they deem unsuitable. 
In the third stanza, the girl is now subjected to the advice of those who wish to shape her into a more easily digested being--a "beautiful" woman. They urge her to "exercise, diet, smile and wheedle," and thereby invert all of her natural qualities. The exhaustion of this playacting wears the girl down until she finally resorts to drastic measures: cutting off her nose and legs to please those around her. 
This, of course, results in the death of the girl. Yet, as she lays in her casket, painted with makeup by the undertaker, she has finally achieved what the rest of the world has desired for her: beauty. It was only in destroying her personhood--her life--that she was able to obtain the approval of others.
This is a disgusting reflection of the kind of subversive thinking that is socialized in young women; girls are brought up to believe that their sole value lies in their appearance and ability to perform as a "feminine" woman. Thus, the last two lines of the poem ("Consummation at last. / To every woman a happy ending.") are sarcastic ones, said with the knowledge that the social systems constructed around women are ones that profit off the death of their dignity.