I think because stories revolves around the protagonist, you find more to root for them whilst the story typically only explores why the ‘villain’ should be punished (ex. Bullying, manipulation & narcissism) to make the ending (usually revenge) more satisfying. The protagonist is given character, the villain is just a plot device.
Many reactions initially were disappointed, wishing Kanna was killed but because we were also given her perspective and it was more detailed than just “argh I tried to kill you so I could become princess at your expense”, many readers like you & I are happy with the ending.
Yeah, good writing isn't only about making a unique plot, but knowing how to make complex characters.
Loved this. I'm gonna be honest, I'm mostly rooting for the "heroine" to destroy the "villainess" in those types of stories, while sometimes I will be intrigued and think "oh, she's powerful" or that I would like to see her point of view, I would be smiling as she gets punished, because then, the heroine would be happy, just like they said.
This time though, I didn't have a favorite. And could only hope for the best for both.