I have to write 10 statements on the cons of dress code. I have 5 for con so far:

1. freedom of expression
2. waste of money
3. dress code can give you meaningless detentions
4. limited choices on what to wear.
5. being different from each other.

can you please help me? i cant think of anything else !

This may give you some more ideas.

http://eric.uoregon.edu/publications/digests/digest117.html

http://www.fresno.edu/scholars_speak/key_and_wilder/