confusion over the pastie

So what is the deal with the pastie? Like how is it that your entire breast other than the nipple can be exposed and it somehow is seen as at least appropriate enough to be viewed on television and in the general public. Cassie and I pondered this while watching the burlesque show at the bar we wandered to after going to our art opening. If someone can shed some light as to why breast tissue is appropriate to be viewed as long as the nipple is not exposed, I would be appreciative.