I've always found "A Piece of the Action" more silly than funny. A planet whose people are so imitative that they'd choose to base their entire culture on a book about Chicago gangsters in the 1920s? Even in a comedy context, the premise is just too far-fetched for me to suspend disbelief.
Of course, not long after that episode aired, we got the Nazi Planet, the American Flag and Constitution Planet, the Roman Empire Planet . . .
TTWT, while a comedy, is much more respectful of the characters and setting of Star Trek, and believable as science fiction and Star Trek, IMO. Gerrold figured out who these characters were, and put them in situations where they were funny because
of who they were, not because they were wearing funny gangster clothes and trying to drive a car.