Also, students during class are usually concentrated in...
school uniforms should be mandatory
I don't think anyone is intimidated by dressing up for school, seeing as how the stereotypical high school in movies does not really exist. Also, students during class are usually concentrated in studies instead of clothes anyway, unless someone is wearing something so ridiculous they can't take their eyes off of it. Even if schools had uniforms, people would still be getting judged even though they would be wearing the same thing. Finally, schools in poor places cannot afford uniforms.