trpguyy said: "Cupid Boy2 said: "In my mind, thinking in terms of "how serious" the subject matter is evades what makes musical theater so special in the first place and not at all ridiculous. Warren Carlyle expressed my thoughts on that topic more concisely and clearly than I ever could when he said, "When you can no longer speak, you sing; when you can no longer sing, you dance."
I'm well aware of this quote, but this is not actually the case in most musicals
"
Not anymore, perhaps, but it was the underpinning of the Rodgers & Hammerstein style of musicals. One of the best examples is the "Shall We Dance?" scene in THE KING AND I. (BTW, if the Warren Carlile in question is the director/choreographer, the quotation predates him by many decades.)
Sondheim and Prince (and others) replaced the R&H style with the idea that content should dictate form, and their musicals as well as subsequent ones use programmatic musical material, songs that comment on the action, etc. and so forth, as the telling of the story and theme dictates.