I'll fix that -- just put me in charge of a school, and I'll make everyone wear overalls. To allow for creativity, it can be with any shirt of choice. And anyone who is caught not wearing both shoulder straps properly hooked to the bib's corner buttons will have the most severe kind of punishment.
Just joking, of course.
While I see nothing wrong with a reasonable dress code (or even uniforms, with "dress down" days), there will always be other things the "trendier" kids will see to make fun of on their not-so-popular peers. If it isn't clothes, it's hair, the way they talk, their mannerisms, and so on. Therefore, I am somewhat indifferent about such an issue.