Here's what I think, as an avid fan of the Batmanverse.
Both Ivy and Harley have the potential to be EXCELLENT female characters.
Both Ivy and Harley are completely ruined and have become extremely shallow because of the decision that sexual appeal should be the main focus about them.
Harley should be an insecure woman with mental issues, in a highly abusive relationship. A terrifying character, who speaks about deep issues that some people face in real life - just like a Batman villain should be.
Ivy should be a crazed eco-terrorist, the kind of people who think "it's better off if all humans die" and who wish gruesome death on people who do as much as eat a hamburger. Again, a terrifying character, who speaks about deep issues that some people face in real life - just like a Batman villain should be.
Instead, what we have is... Harley, the sex-slave who is quirky and funny and sexy and ohmygosh she's soooo crazy that sex with her must be wiiiild.
And then... Ivy, the sexy naked femme fatale who seduces men like a true black widow! She's so hot that literally no men can resist her! And... plants, maybe, I guess?