We should not find it odd that there is a standard song format.
This format has no doubt been fine-tuned over time as musicians discovered that deviation from an accepted and recognized template carried risk.
See, this works the same way with regard to a story.
I mean sure. Nearly anything can be a story.
But most stories – like most songs – have a specific pattern.
Why?
Because it works.
It’s striking how little the basic form of the popular song has changed. The delivery mechanism is in constant flux—from sheets to player piano rolls, to radio, vinyl, cassettes, CDs, MP3s, and now streams. But the emotional mechanics of songs have largely remained the same, whether they’re embodied by Al Jolson’s ivories or Slash’s lead guitar. The verses build up the tension, and the choruses release it, letting the joy in. After two choruses, there’s usually a bridge, also known as “the middle eight,” which is a variation on the verse melody, followed by the final chorus and coda.
-John Seabrook, The Song Machine