We all have bones; they're just not visible very often. If we had transparent skin, we'd think a lot differently about our bodies. Think about the body parts we can see: Fingers, elbows, eyes, noses, ... No one thinks these are gross. But ask people about body parts that's can't be seen like a heart or liver or spleen; often they'd say pictures of these body parts are gross. This seems like a pretty arbitrary classification to me.

This reminds me of the way people look at abortions; if women had transparent bellies and fetuses could be easily seen, I'd think people would tend to have less support for abortions. I am not trying to persuade anyone to change their views about abortion but the fact that fetuses are not visible does make a difference to the general perception of them.