The fact is that there are no unwritten rules in ballet. The rules are very structured, for a purpose. If you want to be a dancer, or even if you just want to take dance classes, you have to submit to the rules. The rules are there for your protection and for the needs of the teacher. If the teacher wants you to wear certain clothing, you should do what he/she needs to help you progress in the class.
As for the "Look at my whatever" concern, here a true fact...everybody knows what's down there, and if they are seriously interested in dance, they don't care what's down there.
Dancewear has to be functional, to allow you to move and to allow the teacher to see your body as it moves. If dancewear is too tight that it constricts your movement, then it's too tight and you need a larger size. If you're wearing sweat pants, you have to realize that sweat pants only stretch so much, and they may constrict your movement. When you see the male dancers in something like "On The Town" wearing what looks to be sailor pants, they are not wearing real sailor pants. Real sailor pants are made out of a constricting cotton fiber. The guys on stage have look-a-likes that are made out of more flexible fabric, with nylon or lycra blends.
You are in an art that requires that the body moves, and that your teachers see how your body moves so that you don't hurt yourself. Go with the flow!
balletboy[/i]