Song is a form of poetry and lyricism is a poetic element. What makes something music aside from just sound - is rhythm. We can see and hear many instances of rhythm, in fact you may have instantly thought of "iambic pentameter". Meter itself lends itself in poetry and music alike!
Japanese has a linguistic rhythmical unit called an onji. It is not like syllables we are used to employing as rhythm in western culture. Simply put, onji is a certain amount of time it takes to pronounce a sound.
In English, words with one syllable can still have different rhythms. Take for example:
One
vs.
Once
Even though "one" and "once" are both only one syllable, "once" is a longer word. (Hell, even the word "verse" is more drawn out than even "once")
In haiku, the traditional 5/7/5 refers to Onji - NOT syllables which makes translating haiku extremely difficult seeing how we do not have a equivalent method like onji in the english language. It is also the reason why haiku is formatted not in the 5/7/5 as many would believe, but merely three lines of two segments no more than 17 syllables.
Haiku also employs the frequent kireji (cutting word) which separates the lines of haiku rhythmically too.
What does this have to do with music and song and poetry?
Well, a lot. The fact is that one of the reasons why poetry and song is saw as a juxtaposition is because unlike Japanese which onji, English doesn't. However we do still have meter, English still have stresses and pauses which accentuates or mutes and offers a type of rhythm.
I love folk music, I love it because it roots from folklore (duh) and it is poetic and prosy. It has the elements of rhythm and lyricism, and yet it is poetic.
My favorite band is The Decemberists because such of the above:
Especially their album Hazards of Love which is a rock opera.