The people who hate Jenny over everyone else are the same people who Skylar over Walter from breaking bad. Edgy 14 year boys who will hate a child sexual assault victim over literal murderers, cannibals, and genocidal maniacs. Misogyny at it's finest.
People hate Jenny the most because they probably have seen a Jenny in their lives. Joker, Hannibal and Vader are too removed from normal life to genuinely hate.
Yeah, I can't understand anyone who doesn't come away with a deep sorrow for her character - certainly compared to infinitely lucky forest. She tries so hard to be a good person despite everything awfull happening to her every single time, he just does what he feels like and every time he has the best luck ever.