I love uniforms and I wish it were plausible to enforce them at any mandatory school. My main reason for loving them is just because it's nice to get up and know exactly what you're going to wear--no thought process involved--because it's the only thing you can wear. I know I'm in the minority with this, though. XD; This doesn't mean I don't like wearing my own thing, but I actually found "Civvies Day" (the days we didn't have to wear our uniforms) to be kind of annoying sometimes. :[ I'd have to actually pay attention to what I was wearing. I really miss having them now that I'm in university.
But furthermore, it's a lot safer. You can easily pick out an intruder in the school or you can tell when someone doesn't belong. In a school of hundreds, this can be more important than you think. When something goes wrong in the cafeteria, it would be very helpful for a teacher on duty to be able to see if there's anything amiss at a simple glance.
The only problem I really have with uniforms is the cost. Since they have to be made out of a good material so they last long and keep up with heavy use, they can be pretty expensive. Factor in that you also need plainclothes to wear when you aren't at school and it can be a pretty hefty task for a struggling family. But as far as I know, most uniform-schools have either second-hand options or "donate your old uniform items" drives, etc.
I've never quite seen the big deal with showing off who you are with your clothes. Clothes may be representational of some of your likes and dislikes, but overall, they aren'y you. I've always found it much more interesting to see who stands out when everyone is supposed to look the same. Do something with your hair (if it's allowed), get a really interesting backpack, or maybe shape your personality to be more open/noticeable so everyone knows your name. I honestly don't understand the people who say uniforms take away all semblance of individuality. Honestly, I'd rather people be able to pick me out from a sea of clothes that all look the same than know me mostly because of crazy things I wear or something.
...And if you don't wear crazy stuff normally, what individuality are you talking about? :( Seriously, at every Civvies Day everyone would be wearing the same thing anyway. Just instead of uniform pants and shirts, they would be slightly-revealing tops and tight jeans (girls) or large shirts and saggy pants (guys). 8| It's all the same either way, imo.