She is the first woman major party nominee. That already puts her up in the pantheon along with Susan B. Anthony, Gloria Steinem, etc.
She tries too hard.
She wanted to be the first woman nominee so SHE could be the first female nominee.
When you become an icon, you can't try. You just are. Hillary will never be a feminist icon like Susan B. Anthony. She only got to where she was due to her husband. Every step she has made was about her. For example, she ran in the New York Senate race because it was a slam dunk guarantee win for her. She stole the seat from a woman who did work her way up there (Nita Lowey).
She wanted to go down in history as the first female President. If she would've died the second after taking the oath she would have been OK as long as she won. That to me is not what an icon should be all about.
She only became as successful as she was because of Bill, really? She was always as intelligent and ambitious as Bill, if not more (she and Bill were supposedly told that she should've been the one who ran for president in the 90s/00s), and she did a lot of work as First Lady of Arkansas and FLOTUS. In fact, she was forced to tamper some of intellectual and progressive edges she had because many defied the First Lady role back in the 80s and 90s (ex. changing her last name to Clinton, changing her look to more traditional, feminine look, not being as brashly vocal about issues she cared for). She didn't pursue a political career early on because she didn't think she was cut out for it, not because she wasn't smart or determined enough for it, or that she wasn't a crucial part in helping Bill succeed. Just because Bill made it on the big scene before she did, doesn't mean she wasn't just as deserving or wasn't just as competent.