Teenage singer has breasts beneath clothes

Why is this Miley Cyrus photo controversial? People reports that Cyrus posed for

...a racy, as-yet unreleased Vanity Fair photo shoot in which she appears to be nude...

Are teenage girls not allowed to admit they have naked bodies? I honestly don't know if these photos would have been made a big deal if Cyrus herself hadn't started this by stating,

I took part in a photo shoot that was supposed to be 'artistic' and now, seeing the photographs and reading the story, I feel so embarrassed.

I guess I'm off America's puritan pulse, but about what is she embarrassed? And why is she drawing this scrutiny to herself?

Vanity Fair article and photos here