I went to a boarding school for a short time, and we had to wear a suit and tie as our uniform.
I was always trying to bend the rules as much as possible though (for example, by wearing a band sweatshirt and saying it was because I was too cold).
I think it's tough for kids at that age to wear uniforms, because it's the age when you're discovering who you are, trying to "prove" that you are an individual, and also dressing in a way you're comfortable with can act as a confidence boost for teenagers too.
BUT if I had to wear a uniform now, I probably wouldn't mind as much.
It is less hassle that picking clothes each day, and it's true that it brings people closer together/breaks down boundaries between students.
Like anything in life, I guess there are pros and cons!