According to the doubtless outdated Sixth Edition of A Handbook to Literature, “poetry” is defined as “a term applied to the many forms in which human beings have given rhythmic expression to their most intense perceptions of the world…. The first characteristic of poetry, from the viewpoint of form, is rhythm…marked by a regularity far surpassing that of prose.” The discussion of poetry goes on to note that poetry is marked by “variety in uniformity, a shifting of rhythms that, nevertheless, return to the basic pattern.”
In short, poetry is patterned, rhythmic language, even when it is not strictly rhymed.
Last year, I read and clipped every poem from The New Yorker, except from one issue that vanished while we were on vacation. Exactly one from the ninety seven poems had a discernable rhyme scheme. A handful had internal rhyme schemes. Most had minimal alliteration, and most were essentially free verse, with largely iambic rhythms and irregular line breaks, presumably for either punctuation or emphasis.
The entire point of every one of them was to convey some sort of image and/or philosophical point. To my personal way of thinking, not a single one was memorable, and none of them stuck in my thoughts or mind.
I’ve also read the poetry in The Atlantic Monthly and in various literary magazines and current anthologies… and the vast majority of what is widely published today appears to fall into the “intense image” or “incident in life creating meaning” model, with very little, if any rhythmic support or rhyme.
Like so much in current life, poetry has become “of the moment,” to be read, momentarily enjoyed or considered, and then discarded.
And one of the reasons why it will be discarded is that those “vivid images” need rhythmic aids and/or rhyme for people to remember them. That’s one reason why rhymed song lyrics are far easier to remember… and why almost all the “modern” poets will vanish as if they’d never been.