I don't think they want the negative publicity of removing the women's divisions from the UFC. But at the same time it's not evidently clear if they participate in something like the Human Rights Campaign's "Corporate Equality Index", so I don't think it's fair to say they're chasing a higher diversity score.
At one point, Ronda was enough of a moneymaker on her own to justify the women in the UFC. I'm sure they saw the viewership/interest in Ronda, Gina before her, and of course Cyborg. Did Nunes sell? I know she was on some big cards, but I'm not sure if she was the driving force on those. Did Holm sell?
"There is no other sport that forces their female competitors down your throat while you’re watching the males compete."
While it's merely sports entertainment, the UFC's corporate sibling, WWE, follows this same model.