JA: “Actually she did tell us that it’s not a problem of tznius but she just made the rule just BECAUSE.”
It had actually occurred to me after I wrote my last post that she might not have given a reason. Sometimes it’s not kidai for mechanchim to give reasons for these rules because the students will just argue with them. If you don’t give a reason, they are more likely to try to figure it out themselves or to realize that the school has a right to make a dresscode and they will understand better when they are older why schools do that.