Come on with the rain / I’ve a smile on my face.
Mentally, I write myself a little story. Of course, sometimes you have a song that says, "Do that." My best example is Singin' in the Rain. Arthur Freed had insisted that the song should be in the picture, but he was very anxious about it.
For a ridiculous analogy, let's take Purple Rain. If you were to put Purple Rain and The Sound of Music on the desk of a producer, he or she would know that the majority of moviegoers would rather listen to Prince. Since they are in the business of making money, no one can blame them. But if it ever came to the decision of making a film like that I'd say, "No." They are very easy films to make, though. In Purple Rain there is nothing complex about the way that they dance. Or sing. It would be a bit boring for an adult to make that film. It just wouldn't test their métier.
There is a certain amount of pornography that exists throughout Purple Rain, but the appeal is obvious. You can really pick that picture apart and see where "A" fits into "B" and so on. It was very wisely done.