>>130863976First problem, she's not allowed to have an edge anymore. Harley was interesting because she was mentally disturbed. She could absolutely still be so as a heroine, making the drama less about her obsession with Joker and more about her trying to do the right thing in spite of having a Joker-influenced mindset.
However, giving her moments of weakness contradicts the grrrl power/harmless fluff vibe of the movies and the cartoon, and that's where the second problem comes, that Harley comics are made more to pander to fans of her adaptations rather than to make her fit in the larger DC universe.
And finally, her powerset isn't interesting enough and functionally makes her a Nightwing clone, but if she got a buff of some sort, comic fans would probably cry mary sue.
I wish for a decent writer to give her new purpose but I'm not holding my breath.