Well this one is not just any old TV show. It's inspired by and in the style of Broadway musicals. It makes sense as a musical.
Which got me thinking, have there been other TV show adaptations that aren't so blatantly in the language of musical theatre, and have any been successful? I am thinking of Cheers (not a musical and def not a success), Little House on The Prairie and I Love Lucy Live On Stage (both directly to tour). Neither was very successful financially. I saw Lucy. With the soundstage/sitcom setup it did read theatre-y.