The points isn't which one you or I find more attractive. The point is a patriarchal group telling young girls they must dress in ways they consider modest (eg, no skirts above the knee, all dresses and skirts must have tights), and telling young boys to avoid girls who dress a certain way. While none of these rules are de jure, the very much are de facto.
Girl: okay babe *unbuttons shirt* *chloe pops out*
Boy: just like I imagined
http://img3.wikia.nocookie.net/__cb20110706060930/degrassi/images/f/fa/Blue-eyes-curly-hair-globes-pretty-girl-snow-thinspiration-white-Favimcom-69980.jpg
more attractive than this
http://2.bp.blogspot.com/-_Oye_WPhUnM/T3dzo_6L6xI/AAAAAAAAFPY/WNDPFfxNi3s/s1600/1273381688983.jpg