To sum it up, the following of a certain high-school dress code, such a uniform has many positive aspects to it and can improve the learning experience.
It is better if you outline your essay before writing it.
Outline will help you to keep all your ideas intact and will take away the pressure of thinking what to write next.
They learn to value other people for their personal traits and qualities, rather than for such superficial aspect as dress.
Moreover, the common uniform can help to stop bullying that became a big trouble for high-schools nowadays.