Ivy in the cartoon was a cool seductress who used her beauty, sensuality, pheromones, and wit to control everyone around her so she could feel in power and get what she wanted. This is who Ivy's supposed to be.
Take her relationship with Harley in the cartoons. The cartoons would often subtle point out that she was just as bad as the Joker, because she'd often try to dominate Harley, both by ordering Harley around and by attempting to "teach" Harley how to be a better woman, using herself as a model, because of course in her mind she was better than Harley in every way. It was a power trip.
It's just that Harley in her clueless and ditzy manner would totally ignore Ivy's commands and teachings, something that always drove Ivy up the walls. Specially when Harley messed something up and all of Ivy's perfectly laid out plans went tits up. Ivy's control over the situation would be gone.
That's something that the modern writers completely ignore about their dynamic. Ivy's all about having control and power. She wants to feel as empowered as men. She's a control freak. FUCK, SHE HAS MIND-CONTROL POWERS! IT's that obvious.