It isn't only the females voice, it is the way he writes some females too. I am on my second listening of the series and I am seeing it more for what it is. I like Sanderson's stories a lot but some of his characters are not very palatable to me. The females voice doesn't help it. I think he does a great job of writing Kal in those books and he even does a good job with writing Syl, not a fan of Chelan or however it is spelled.
Not always females either. I loved the first Mistborn series because Wayne is not an enjoyable character, he is cumbersome for the audience to follow. I know it is how Sanderson writes combat in that series, but Wayne is overwhelming with humor just gets old. I kinda like Wax and Mr Suit was fitting.