PS it's very common for parents to put limits on what their offspring wear, etc.. It is in their judgement in the best interest of their offspring, even if often the offspring disagrees.
Oh, and of course the boys will notice your legs, and if you flash your underwear that'd catch their interest too. Which may or may not be part of the appeal, given we all would like to be admired. Probably best to put up with your parents' decisions though. You will have plenty of years as an adult when you can decide for yourself what is best.