I have always understood that poetry does not have to rhyme. The point being made was that the lyrics of DOT do not rhyme yet by way of the poetic features that you mentioned, it is still poetry :-)

I think Kipling made a witty point about rhymes in his poem 'Cells'

I left my cap in a public-house, my boots in the public road,
   And Lord knows where, and I don't care, my belt and my tunic goed

:-D