It's different for girls. With a uniform policy, they are now saving 30+ min a day choosing what they wear. Dress codes aren't freedom of expression, you can express (and show) all you want to the public elsewhere. Dress codes and uniforms not only regulate but keep it a learning enviroment at schools and where ever else. Try wearing fishnets and a leather jacket to work; express all you want, things aren't going to go well. In a sence, SOCIETY itself has a dress code.
The way they spend their time is up to them. If they want to spend 30 + minutes figuring out what to wear, whatever. If they don't want to it's simple, don't; we don't need a dress code to control our own time schedule.
I have seen many different random things people chose to wear in a public school, is it distracting? Yeah, maybe for a couple minutes, then what's distracting? The kid in the back throwing paper. Let's face it, clothes don't honestly cause a big deal unless everyone keeps complaining about it.
See the thing is I'm all for companies having dress codes if they want. If they pay you and want a uniform, that's the employers choice. The reason I feel there shouldn't be dress codes in school is because you don't choose to be there (I'm not saying you should have the choice to go or not) they shouldn't be able to say what you can and can't wear.