>>712680171 (OP)1) Nasu used to be obsessed with the "tainted heroine" trope where one of the girls has been sexually abused and/or has a dark, violent side to her personality as a result of a shitty upbringing and Kohaku derivatives like Sakura show up in several of his works because of it.
2) Sakura is still actually pretty popular, even if the least of the three main FSN heroines, so yeah it worked out pretty well.
3) She did nothing wrong btw