Arguments FOR:

It's practical because you don't waste time.
You need just a little cupboard in your room. So you have more space for other things (a big bed, ...)

Arguments AGAINST:

When you are organized, you can prepare your clothes one night before.
Uniforms are not comfortable. For example, in P.E. (sport), it's not practical to run.
When it's cold or hot, you just have one choice.

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Vocabulary:
a counter argument
a cupboard