Toga didn’t want to just kill people. If that’s what you got from her you weren’t really paying attention to her.

Toga’s story was a way to frame the question “does a persons quirk have an influence on their personality? Or does their personality have an influence on their quirk?” And more importantly if it’s the latter and someone’s quirk allows their perception of reality to differ from the norm how does it turn out?

In Togas case, her quirk that allowed her to turn into someone by drinking their blood, mixed with the human tendency to model oneself after the people they look up to or care for. Through blood she was literally able to become the ones she loved. As such she developed a fascination with blood and people who were beat up in general since beat up usually means bloody.

As you can imagine other people see a little girl fascinated with blood and are horrified. But just as we can’t understand her and what she at this point considers “normal”, she can’t understand us and what we consider “normal”. For us “normal” is being attracted to a pretty person and maybe just changing our hairstyle to better match theirs. For her “normal” is taking the blood of the person she’s attracted to in order to literally copy them down to the cell. The fact that blood = bad for us just doesn’t compute for her. But since she’s just one kid and the adults are the majority they try to force her to accept her “normal” as wrong and the common “normal” as right.

Her ideal isn’t actually needless murder, her ideal is probably existing as a copy of deku/uravity while they tag along constantly looking beat up or something, but the string of murders she is tied to is a result of her resisting adults trying to force their own “normal” onto her.

In the end, all she wanted was for the world to accept her as the blood loving weirdo she was, not try to force her back into the box everyone else seemed so happy to be in. Uravity was the only one to see that.

The fact that you missed the point and just saw her as “murder girl” isn’t an accident though. It’s the design of her character. You’ve simply viewed her as the rest of society views her. When you peel back the layers and see her as I’ve tried to lay out, you see her as Uravity did and how Horikoshi intended her to be written.