My 2 cents:
One problem with uniforms is that most of the "school uniforms" I've seen in stores are very cheap quality--thin white shirts you can see through, and poor workmanship. Ugh!
On the other hand, I once saw a photo of a group of school children in India. They were all in uniforms. I was surprised at a certain optical effect: because all the clothes were the same, I found myself focusing on their faces. They weren't a group of kids; they were individuals!
Supposedly, most American kids oppose uniforms because wearing uniforms will take away their individuality. Yet, when left to choose their own outfits, woe to anyone who wears something different from the "cool" brand or the "in" ugliness! In other words, they all have to dress according to the "cool" code, anyway!
So, I think the real issue is that students don't want the authorities telling them what to wear. I wonder, what would happen if the school board told the students they HAD to wear ratty, baggy jeans with skimpy T-shirts sporting nasty slogans?
By the way, I've known some people who are involved with prison chaplaincy programs in California. They told me that if you visit someone in a California prison, you mustn't wear blue jeans. Why? Because blue jeans are part of the California prison uniform, and visitors aren't allowed to dress like prisoners!