why are prophecies always in verse?

So I was watching this animated version of 'the Hobbit' the other day which I have loved since my childhood. It really is great, Joe can attest. But what this one part made me think. During the movie they would put the poems/songs from the book to music, funny '70s style music, and sing it as part of the soundtrack. And one such song was part of the prophecy of the Mountain King's return:
"The streams shall run in gladness,
The lakes shall shine and burn,
All sorrow fail and sadness,
At the Mountain King's return!"
I thought it was interesting how it actually looked to have the prophecy fulfilled (like and unlike real prophecy because Tolkien wrote the prophecy and the fulfillment) with a dying dragon falling burning into the lake, etc. I also thought, "Wouldn't it have been plainer to say 'When Thorin, grandson of the old King under the Mountain, returns to the Lonely Mountain, the dragon will be slain above Laketown and things will return to cleaness and happiness'?"

Or consider this one, from the Lord of the Rings:
"All that is gold does not glitter,
not all those who wander are lost;
the old that is strong does not wither,
deep roots are not reached by the frost.
From the ashes a fire shall be woken,
a light from the shadows shall spring;
renewed shall be blade that was broken,
the crownless again shall be king."
If you know the story, work out what it was like for this to be fulfilled.

And then I got to thinking about some stuff I'd heard describing poetry, how it can capture subtleties which prose cannot, and how a girl would rather you read her a poem you wrote about her than a list of her attributes and habits. And I remembered the Bible, how a lot of prophecy in there is written poetically. This was my conclusion:
The subtleties of a poem about what is going to happen in the future are easier to live out within the dance of a God who has written the end already and myself being free to do as I choose. For Frodo, about which there was a prophecy that a halfling would carry Isildur's Bane, he could actually live within the poem. If on the other hand, he had read Tolkien's books and then tried to live his life, he would probably go crazy. And so would we, if prophecies that we lived out were written as history.

On still the other hand, Jesus sometimes spoke prophecy like history: "I will be handed over to the Gentiles; beaten, mocked, spit on, and killed. Then three days later I will rise from the dead."
And his friends said to themselves, "Hmm, what does this poem mean?"