LOL!!! Yes, her uniform choice was probably a section retcon..... but.... she was going to quit TOS after the first season anyway because of her notoriety. Roddenberry asked her to stay because of HOW her character fit in to the theme he wanted to tell, but she told him she would think about it over the weekend.
That same weekend, she went to a Civil Rights fundraiser for MLK. Was approached by him and was told she was an inspiration for him, and he was one of his greatest fans.....
She stayed on TOS, instead of going to Broadway because of that. The rest is history..... and the sexiest Red Mirror uniform, and the 5th (LOL@!) nationally broadcast interracial kiss on television!!