Harley benefited from being associated with Joker, who people associate as one of Batman's primary antagonists, but the staff also used a lot of her appearances to show different sides of her personality and persona dilemma with her feeling unappreciated by Joker and trying to prove herself, her trying to redeem herself when given the chance by Batman, her questioning if she needs recognition or redemption when with Ivy, etc so she feels dynamic.
Leslie has a few similar things, mostly from comics so that cuts a chunk of spectators to her appeal, but how compelling the premise and payoff is tends to pale in comparison to the other rogues like Luthor, Metallo, Parasite, Bizarro, etc.
Her teaming up with Ivy and Harley has potential, I think they should have made Livewire like Inque, a sort of supervillain for hire. It'd make her seem more imposing if her appearance implied she was considered by someone necessary muscle, instead of just using her powers for aimless vandalism and intimidation. Her background being precisely someone who just riles people up sort of makes it difficult to buy her as much more though.