If you look at the live-television clip of Comden and Green performing "Carried Away" that I posted in the On the Town Reviews thread, you will get a sense of the kind of broad comedy that Betty Comden and Adolph Green enjoyed. They knew that musical comedy needed that as contrast to the tender and sentimental moments that came in the love songs.
It may surprise you, but Leonard Bernstein and Jerome Robbins also enjoyed that kind of comedy and strove to attain it themselves in comic numbers like West Side's "Officer Krupke" or Wonderful Town's "Wrong Note Rag" and conga number or some of Robbins's comedic ballets.
John Rando let Jackie be inventive because it was the right thing to do.
Go watch the clip of Betty and Adolph--or some of the MGM movies they wrote screenplays for.