didnt think that she would show her boobs

Most recently (prior to Shameless that is) she did an indie called Dare that came out in November 2009, about a month (maybe less) before she was cast in Shameless.

But a million other actresses would have taken the part in Shameless as well. It's a great part in a great series. It lets her work with talented veteran actors on a critically acclaimed network and mix up comedy and drama. Most actresses would be excited by a chance like that. Were Emmy's movies generally hits? No. Did she probably want to break out of the good girl typecasting mold? I'm sure she did. But she could have done that by "leaking" a sex tape or appearing nude on the cover of a magazine. Instead she did it by taking a very different kind of role that required some nudity, but also a lot of acting chops. I don't any ulterior motive here.