Personally, I think young actresses just should go ahead and just get it over with when they are young. That'll shut the fanboys up, and you can go on and to whatever you want to do.
Course, for some actresses, that's the only thing that they really have going for them. Not sure if I can say the same about Ms. Portman.
Course, considering that she's playing a stripper, you gotta assume that showing some flesh is part of the role.
Initially she asked Nichols to cut the nude scene entirely as she didn't feel comfortable with it. So if the topless scene is left in we should be happy we even get that.