Children should definitely have to wear uniform.
If children didn't wear uniform it would cause more work for the mother as she would have to wash and iron their different set of clothes nearly every day or else the child would have nothing to wear. Also as children grow up and turn in to teens, they become more adult and may start dressing very differently than how they would have when they were younger. Girls for example will want to start impressing the boys but with no uniform they can wear what ever they want. For example short skirts, tight trousers and crop tops. Uniform is a good way to prevent the girls from doing this. It means that they have a certain thing to wear 5 days a week. It also doesn't mean that they need a new outfit everyday for both boy and girl. Also uniform is a good way to present the school as it shows that they are a constructive, sensible and well behaved school.
School uniforms can be annoying and sometimes you will run out of clean clothes. If you do laundry each weekend or every other week, you will have clean clothes to wear, but if the clothes become offensive there should be a system. First time you are caught with profane or inappropriate clothing you will be given a warning. For the second time you will be sent home to change, or just stay home. For the third time detention, and for the fourth time you alone will be given a uniform to wear. It is that simple as long as you keep it under control.