I haven't read all the responses, so this is just my take on things:
The pics Leibovitz took of Miley Cyris are artistic, beautiful, and deliberately controversial. The images are consistent with Leibovitz's aesthetics and her ability to generate buzz. They come as no surprise to me, nor should they be particularly surprising to anyone who is aware of Leibovitz's or of Vanity Fair's work. Leibovitz is well-known for pictures that confront our notions of what is beautiful, what is sensual, what is sexual, what is intimacy, and what is fantasy. (For instance, she took the picture of the beautiful, pregnant, naked Demi Moore for Vanity Fair. And she was hired by Disney for its Year of a Million Dreams campaign to recreate images from "children's films" with adult celebs.)
I also think that neither Miley nor her parents or her agents were or are unaware of the cultural capital of having a picture taken by Leibovitz, or of the types of pictures Leibovitz takes. (Let alone the type of photos Vanity Fair publishes.) She is well known for her work with celebrities and her ability to create striking images is valued by both celebrities and companies alike. I can only imagine that the apologies & explanations are more about the response to the images than about the images themselves. I, for one, think no apologies or explanations are necessary and only serve to focus more attention on the pics.
What's more, I think the general negative response to the pictures is disproportionate to images themselves and their impact on Miley's perceived child & adoloscent audience base. My reasoning is based on where they're published (these images are not at all out of place in Vanity Fair), who the intended audience is for that peridocal (as opposed to the general Miley Cyrus audience base), and the type of pictures these are intended to be (fashion, celebrity photography).
What I find most interesting in this whole discussion is that there appears to be more consistently negative public & media outcry regarding these pictures then there have concerning other recent Leibovitz photos. There seemed to be very little furor about Leibovitz's Vanity Fair cover depicting a clothed Tom Ford and naked Scarlet Johannson and Keira Knightly; it was, if I remember correctly, only briefly critiqued for its gendered/sexist implications. And the discussion about Leibovitz's Vogue cover with LeBron James & Gisele Bunchen, which spurred conversations about its possible invocations of racist imagery, was largely dismissed in many public circles (including this board).
So I guess where I stand is that I see all these pictures as artistic, but found the latter two examples even more disturbing for their implications. Yet he opposite seems to be true as I read articles, new reports, and online discussion. So I think that's suggestive of where we as a culture are--we're more discomfited by images--as I read these photos--of adolescent sexuality than we are with images of gender stereotypes, sexism and racism. And I'm more interested in why THAT is than in the photos themselves.