One of the rules poets can break is the format of the stanza. Traditionally, poets wrote to form, here the poet wrote to keep the song and to remain on topic with what he wishes to say. His life ended just as the Great Depression hit, so perhaps the bad times he speaks of reflect that time period. The two lines:
"Oh, that mankind had less of Brain and more of Heart,
Oh, that the world had less of Trade and more of Art;"
appear in the last stanza, showing almost hope despite the octopus crushing the throat of poor art. These lines serve as a turning point for the poem that ties back to the first stanza, before going back to being bleak. Contrast it with the joy in the video below.
Assignment: Write a poem about the business of poetry, whatever you have learned about the struggle between work and art or music.
Here's a video of Ray Charles performing James Weldon Johnson's "Lift Every Voice and Sing."