The point is not about expressing yourself or looking good. Those are definitely positives.
The point is about dressing distractingly. Say for example the man in the picture takes class for you, are you telling me his outfit won’t be distracting for you ?
It is distracting because it is out of place for where it is worn, school. This man could come like this for a party and he would be a hit.
The same applies for students, be it from any gender.
The counter argument I always see is “boys should be taught to control”. While this is true and a certain amount of decency is expected from everyone even if they find someone attractive who is dressed non distractingly, the other side of the coin is that someone who is dressed inappropriately to the place (school) could distract “boys” even if they don’t find the person attractive. This it is definitely the problem of the outfit.
In short the problem is the “everything goes” attitude