The best thing about tights & leotard for the studio is that your body is completely free to move, your "crown jewels" aren't haning out, you can see most everything, and you're ABSOLUTELY NOT naked or lewdly dressed. You need to feel safe in the studio, to expose your body like that. However you move, you don't have to worry about your shirt falling up, or your pants falling down, you can concentrate on the dancing. It's very freeing.
Nylon is also a non-abrasive fabric. Nylon tights eliminate chafing between the legs. In ballet, you lear to move your inner thighs against each other, which would quickly become uncomfortable without nylon in there.
-- Bob[/i]