Frank Rizzo When a character in the new musical “The Heart of Rock and Roll” tries to convince his ex to leave her job at a factory that makes shipping materials, he is stunned: “Oh, my god. It’s cardboard!” But there can be real appeal to the humblest of materials — and the same can be said of this unpretentious, silly and, in the end, rather fun show. For all the familiar jukebox musical templates of thin characters, unsurprising plot developments and oldie pop/rock songs shoehorned into the narrative, there’s something to be said for simple packaging that knows what it is and does it well.
