Marge Piercy's poem "Barbie Doll" is a condemnation of the unrealistic expectations of beauty. The doll, Barbie, was once the iconic representation of what every woman should be. Things have changed, and the term is now used more as a pejorative (an insult) regarding women who have overemphasized their physical attributes at the expense of anything else--to their own detriment.
In this poem, the speaker functions as an impartial narrator. In fact, the tone of the poem is such that the speaker appears to be telling us a fairy tale--a tragic and twisted fairy tale, to be sure, but a fairy tale nevertheless. The narrator sets the tone and pattern in the first stanzas as the speaker lists the very "normal" attributes of our heroine, known only as "she":
This girlchild was born as usual
and presented dolls that did pee-pee
and miniature GE stoves and irons
and wee lipsticks the color of cherry candy.
The narrator's tone is matter-of fact and non-judgmental, just like a narrator in a fairy tale. That tone doesn't change when the poem takes a drastic turn in the next two lines:
Then in the magic of puberty, a classmate said:
You have a great big nose and fat legs.
The speaker, then, is a non-committal storyteller who shares this tragic fairy tale with us, but without commentary.