no not at all, the only reason i can think this rule is in place is so that bra straps won't get seen if you're wearing a tank top or something.. which is ridiculous, but dress codes are usually pretty stupid in terms of covering up skin and being "inappropriate".

damn gurllll ur shoulders turn me on so much said by no one ever

Because school officials are scared that boys will get turned on by even a little skin showing. Sad but true.