Yeah I heard it was Esme Bianco who didn't want to do the nude scenes anymore, and that is why the killed her character off. That honestly makes the most sense to me, since she was an actress that almost every scene she was in, required her to get naked. She didn't once get naked in season 3, and seeing how they used her I can understand why she would be afraid that the nudity would be all she was known for. Anyways, I do agree the path they have chosen for Tyrion and Shae is a bit lame, and it worries me with how it will effect the final outcome of their story.