There have always been fashions in poetry, and the current fashion is for free verse. Even the most cursory look at the latest poetry magazines will reveal the unyielding trend for non-formal, unrhymed verse. The leading poetry magazine, Poetry Review (the organ of the Poetry Society) features no rhymed verse.
Even Milton pointed out how rhyme could act as a limitation in the writing of poetry - and there are no rhymes in Paradise Lost. However, there is a formal structure in that Milton writes in blank verse, not free verse: that is unrhymed iambic pentameters. This technique in a more flexible form has been used by T.S. Eliot.
