I figure it's more up to the actress whether or not they appear naked.
Has Sophie Turner been topless at all? I can't remember if she was, and I don't think she had a career prior to the show.
On a side note, I seem to recall Emilia Clarke being more of a theater actor prior to the show.
Well, I think the concept is that Sophie Turner was a young, adolescent, while Dany was portrayed as a young woman. We saw Dany getting aggressively handled during her wedding night against her will in the first season and people said little, we see the same thing happen with Sansa's character (who is now older than when Dany married Drago) and nownthere are screams against rape and poor treatment of women in the show.
I don't know... I have no problem with any of the mature content in GoT - nudity, violence, sexuality or profanity - because these aspects of human nature occur every day in the real world. To have a story that deals with war, death and power and not acknowledge that these elements exist is shielding oneself from the reality of how the world really works.
But that's wildly off topic.