I know what you mean .. and I definitely agree that her style should evolve for her styling work .... but for her personal style - she seems to have found her look and sticks with it. I know when I'm her age I will want to have my look sorted and not be persuaded by a different trend every six months and just know what suits me. The thing is too is that we're saturated with that look (black skinny jeans, leather, blazers, black, grey, white) she wears so often because of the exposure Balmain, Isabel Marant (and the like) have been receiving.
Also don't forget her job is to be 'behind the lens' ... its the fashion and street style blogs that have noticed her and put her in front of the camera. While we can appreciate her look, I don't think it's fair to critique her because she wears what she likes and what suits her. She doesn't dress each day for the cameras or to be seen in the latest looks .... it's her styling work that should be critiqued.