Purpose of uniforms: Enforce equality and unity. Make everyone dress the same and hopefully they will realise they aren't so different, and that they should work together.
For 12 years I was in school wearing my uniform, detesting it the whole time. But actually now I realise that it was a good thing. I was friends with people I never ever would have been, and I think the uniform helped me to relate with them. I have seen some of those people since I left school, and I know they would still back me up.
I think that if we didn't have uniforms I would be wearing my shiz, and they would be wearing their shiz (eg my mate is a goth, and I would probably never talk to him if i met him for the first time and he was in full goth gear).
So yeah< I think it really does help.