I wonder about the "shameful" aspect. Is it not rather an object of modesty -- as opposed to shame? I am not in any way ashamed of my sexual organs, but I'm very reluctant to show them to other people. I avoid group showers, for example.
In my opinion, yes it is. There is propensity in our society to view virtues as shameful, which seems inherently contradictory to me. As a witness to this, I note the almost violent reaction to teaching abstinence by a very vocal group in our society. Perhaps the 'popular' understanding of shame/freudian psychology is the source. I'm not sure.