You do realize that copyright is a legal structure created and determined by the government, and its terms can be modified and defined as to public policy, right?
Not per se. Article one explicitly states that intellectual property regimes are to be established for the purposes of promoting useful sciences and arts. It's not a carte blanche prerogative of the legislature.. It has a designated purpose. Simple act of allowing someone to see you naked is not an act of an artistic performance. Doing so for the purposes of coitus is a biological imperative (akin to going to a doctor to get a check up). Agreeing to be observed carries with it agreeing to have someone remember the observation. And the observer should retain the copyright of the observation(if (s)he, for example, talks about it) or recording because observation and recording are the only parts of the act which have any artistic merit. Simply showing up to be there naked to have your biological imperative fulfilled is not an artistic or a scientific endeavor. So it merits no intellectual property protection.
He who has but four and spends five has no need for a wallet.