By Bonnie Stiernberg On Thursday, Vanity Fair unveiled the cover for its 28th annual Hollywood Issue, and the backlash was swift. The image features Nicole Kidman sporting a two-piece look by Miu Miu that commenters on social media immediately started likening to a “sexy schoolgirl” — a baffling styling decision for a cover meant to honor a 54-year-old woman for her professional accomplishments. “Why is this distinguished adult dressed as a schoolgirl?” one Instagram user commented on Vanity Fair‘s post revealing the cover. “One of the most prolific actresses (and also most beautiful) and she …