Yes, absolutely. It is necessary. School is a place of learning, it should be of least concern what to wear and having a school uniform suppresses this 'pressure'.
Yes, and I don't think that they need to wear uniforms since they are being prepared on what they will face in the future. Yes, people will recognize the students with high social statuses in that state but in the future when they are working, they will be facing a lot of powerful faces and that will be the only time they will be feeling the pressure since they are not used to it.
Uniform is great, yes but the fact that we don't teach them how the reality works will also be the reason of their fall. Let them see their differences to other people so they can acknowledge them and think of his or her own way to reach them and maybe pass those people in the future or maybe in his or her career.