I may not ever get my poems published, but I may never get my fiction published if I don't write completely unrelated and voraciously genred poems.
Writing poetry makes you think of all kinds of things one would never think of while writing strictly fiction. New and brilliant metaphors pop out. Deliciously aesthetic syllables come together.
It's kind of like how I read Pride and Prejudice and suddenly my writing had much to recommend itself to others and sounds very proper.
At least to me.