Wicked, in case anyone’s living under a rock, tells the story of the “Wicked” Witch of the West, Elphaba, from her own perspective, focusing on her childhood friendship with the “Good” Witch Glinda. For those of you who’ve read Gregory Maguire’s novel, don’t expect the same intriguing moral ambiguities, complicated characters and dark tone from the show now playing at the Kennedy Center. This is, after all, a musical. The fairly dramatic revisions from the…