I heavily disagree with Yae and maybe Takemiya Jin herself assuming that is her perspective. Cosplay isn't appropriate normally because it is too flamboyant or too suggestive for normal attire in a school setting. Her outfit is neither. Wearing a long skirt and otherwise normal outfit is not remotely equivalent, and it sure as hell isn't "asking" to be raped, which is what seems to be implied here.
Beyond just the victim-blaming mentality of this perspective, it just seems backwards. It's like saying that somebody wearing a tuxedo suit to school is asking to be raped or is in violation of school code.
It doesn't even make sense.
The only consequence of wearing this outfit should be that you stand out and are maybe shunned by a minority of idiots because you aren't following fashion trends, which is probably to your benefit because you didn't want to be friends with those people anyway.
I think it's more on meeting social norms by changing something that isn't very critical to who you are as a person. Sakura is only imitating Yae and wearing that outfit isn't really something that significant to her identity (considering how quickly she was ready to change things up) so what's the point of putting herself in danger for that?
There are valid arguments about victim blaming but it's also important to understand Yae's point about how you present yourself to the world having an impact on how people perceive you: if you dress like a crazy person, people will think you're a crazy person and likely treat you as such. There is also some responsibility on your part that you still need to consider.