I thought I already stated why? You have to kill her for more corruption points and it was really messed up when you saw her thoughts. For someone who likes her, like myself, the high corruption route requires you to kill her and Danica as well. Obviously you're not forced to killed them but if you want all the corruption points, you'll have to. For my main, that's not something I'm willing to do as I like Danica and Bailey. I'll play into corruption but I'm not going that far with it.
For my side playthrough saves though, that I started, high corruption changed my views because it's pretty wild when you see more details about your monster parent, gain more info and become better with your powers overall(MC was able to use Ella's shrink ability she had just shown him with easy on 2 people that you kill). If I didn't have to kill either of them, Danica and Bailey, it'd be my main since I'm more interested in the Monster aspect and power overall for my character.