The dress code is a rule that confines you from showing people who you are. It does not let them know about how you feel about the world. They confine you for doing what you want and I don't see the point in it. Really tell me what is it.
Inequality abounds without controls and rules, and such inequality is welcomed in today's over-choked education institutions were students in public schools number approximately 25 to 35 per class, when those most productive that excel in school, could be enjoying a greater allocation of limited teaching resources to achieve their fullest potential, had they been placed in a smaller class. So, to have differences so stark that is to be seen immediately as flashy patterns, exposed ample cleavage, obvious brand labels, such that those proving incapable of adjusting to the social hierarchy within the school will be ostracized and trampled on, weaklings as suggested by their appearance, eliminating themselves as threats, facilitates those who are able to acclimatize to the implicit competition held among students and succeed at their studies, to have greater access to learning, massively improving their future prospects as they do better on the SATs, the ACTs and the APs, segregating themselves as the elites amidst the inept who can specialize only either at building the body muscles, or increasing their intelligence. Competition will always produce winners and losers, and so rather than equally apportion each and every student scarce resources, focusing only on those with the greatest chance at success makes for better people and better schools.
Looking different separates you from the group. The more different you are, the less acceptable you are. If everyone dresses the same, everyone is equal.
Get use to it. When you grow up, you will have a job that requires you to look a certain way. Right now, school is your job. If you want to express yourself, do it like adults do. Do it on your own time. You could look at a dress code just like the rest of school. Trying to prepare you for life after school. See, that is what school is suppose to be and not some social meeting grounds.
At a public school (trust me I know about this) kids get bullied for their clothing all the time. If you wear un ugly sweater kids will be mean. Its just what they do. Uniforms allow kids to be equal therefore taking away that disbalance in power caused by different clothing.
A school is designed to prepare the child for adult life. In life you are expected to dress a certain way for certain professions. This is why a school uses dress codes to get the students prepared to also use dress codes in the work place. To do away with the dress code in schools will simply be another thing in a long list of reason students entering adulthood are not prepared.