No. In real life, people aren't all the same. They don't look the same, they don't think the same, they don't act the same...if school is to teach kids ANYTHING about life after graduation, uniforms cannot be instated. If the administration is too lazy to discipline students who dress inappropriately, that's THEIR problem. Let the vast majority who dress correctly be allowed to wear what they want.
Furthermore, administrators should not fool themselves thinking that uniforms would prevent cliques and bullying. These things are caused by the personalities and behaviors of students, not by what they wear. However, what they wear is influenced by their personalities, obviously, so that's where that misconception comes from.