The Qur’an’s form differs from the full set of established Arabic poetic metres and rhymes. That difference expresses a distinct rhetorical character, not an abandonment of audible beauty. Its sonic possibilities are wider than the obligations of any one fixed poetic genre.
A new form of expression cannot be judged only by asking whether it imitates an earlier metre. The more important test is whether its diction, sequence, force, and meaning suit the purpose of the speech.
The purpose of address: the Qur’an is not framed as a bid in a poetry competition. Its teaching, reminder, warning, and guidance govern how its sound and structure are understood.