Being able to decipher the tone of a piece of writing is crucial to being able to decipher the thematic message of a text. This is absolutely true for analyzing poetry.
Love it or hate it, poetry is unavoidable in the secondary ELA classroom. I, for one, am a HUGE lover of poetry but fully acknowledge that it can be annoyingly cryptic at times. Reading poetry reminds us that not all texts are meant to be beat "with a hose to find out what [they] really mean" like in the Billy Collins poem "Introduction to Poetry."
You may find yourself in agreement with Frost's famous quote when it comes to teaching poetry in the secondary classroom. However, love it or hate it, poetry can play a helpful role in teaching students how to write! Famous poems can serve as mentor texts for students and showcase key literary and rhetorical devices in action.