Barbie is never mentioned in the poem. What do you think is the meaning of using the term "Barbie Doll" in the title?

I think that the iconic reference to Barbie is quite
evident in Piercy's poem.  The construction of the Barbie Doll by Mattel is used to
reference how women's identities are constructed by a patriarchal society.  In this
light, the presence of Barbie as an icon is something that has been absorbed by women
and the social order that relegates them to the status of the doll.  Piercy makes this
present in the opening lines of the poem.  While we don't see the Barbie doll, it is
present in the first 2 lines that girls "are presented with dolls that did pee- pee." 
In this seemingly harmless act, Piercy is bringing out the idea that women's vision of
self are constructed from the earliest of ages. The presence of "lipsticks the color of
cherry candy" enhances this feel, as well. Women learn early on what society believes
they are and this message is reinforced throughout their lives.  Just like the Barbie
doll who is constructed for particular aims and to represent a particular state of
being, women's identities are constructed in much the same
manner.