Linda Williams, in her remarkable book of film criticism Hardcore, pointed out the similarities between pornography and musicals as genres, that just as in a standard Broadway-type musical the story exists to keep the songs from all happening at once, to showcase the different types of song, in pornography the plot exists only to keep the sexual acts apart. They're what you've come to see (the songs, or the sex), what you'd feel cheated if you didn't get. It applies to other genres too, in any medium.
Musicals = porn. This observation may change my life. Or at the least cause errant dirty grins in rehearsals.