Poetry is a medium that is suited to the transmission of wisdom which is the aim of philosophy. Compression and densification of meaning is its primary mode. The full range of reference of the word is used and the metrical form makes it memorable so that dwelling in the the poem is made easy. This dwelling is necessary for the meaning in all its complexity to emerge. Moreover the alien rule of metre forces the mind away from the economy of effort which is cliché and the new way of saying something is the mother of new thinking.
cf. Four Quartets by T.S.Eliot