Stephen Whiteside wrote:The notion that there is a 'poetic' way of saying things which is always the best
That's not Heather's proposition at all.
Heather is alluding to rhythm in poetry. Spot on, I reckon. Poetry can have metre but not have the rhythm to be really effective poetry ( I got that from Charles Hartman, Professor of English, Connecticut College ).
Charles Hartman says that metre, with it's stresses and "slacks' is NOT the same as rhythm. Once we get that, we are on the way to understanding how poetry works differently from non-poetry, as it were.
It's not that there is a poetic way that is always best. There is a poetic way that has the rhythm that makes poetry different from prose or plain narrative. So I agree with what you say. The most powerful emotions might well be expressed in "flat" language, if that is the rhythm that expresses that emotion.
Winston Churchill's famous speech " this was their finest hour " " Never in the field of human conflict has so many owed so much to so few " ( hope I quoted correctly

)or Abraham Lincoln's " So that government of the people, for the people and by the people may not perish from the earth " These things aren't metred, but they are just ordinary words made into just the right rhythm, and have become unforgettable quotes.
And before I get beaten up. I have a loooong way to go to grasp what all of this means, and looooong way to go to be able, if ever, to put it into practice.