Why Tell Stories in Songs?

Moon River will be a good example of a ballad. After watching Breakfast at Tiffany's, I am aware of the mood of the setting created in the movie. The melody and the lyrics give a sense of a harmony to the feeling of Tiffany who sings at the balcony. In my opinion, telling stories in songs helps create the mood for the background and the personal bubble for the listeners. 

LYRICS: 

Moon river, wider than a mile
I'm crossing you in style some day
Oh, dream maker, you heart breaker
Wherever you're goin', I'm goin' your way

Two drifters, off to see the world
There's such a lot of world to see
We're after the same rainbow's end, waitin' 'round the bend
My huckleberry friend, moon river, and me
[ Lyrics from: http://www.lyricsmode.com/lyrics/a/andy_williams/moon_river.html ]
(Moon river, wider than a mile)
(I'm crossin' you in style some day)
Oh, dream maker, you heart breaker
Wherever you're goin', I'm goin' your way

Two drifters, off to see the world
There's such a lot of world to see
We're after that same rainbow's end, waitin' 'round the bend
My huckleberry friend, moon river, and me

(Moon river, moon river)