Why haven't we gotten a musical "Doctor Who" episode yet?

The music men at AVbyte have released a number of Broadway-inspired pop culture parodies, including The Walking Dead: The Musical and a medley of hipster Disney princesses. In their latest installment, a freshly regenerated Doctor sings about his adventures in Times Square. It begs the question: when do we get to hear… » 11/03/12 1:00pm 11/03/12 1:00pm