If I were to defend the quote given from Dead Poets Society, I would note the separation between the affairs of man and the affairs of the heart and mind.
"Medicine, law, business, engineering" are elements of the world-at-large. Here lie the heavy burdens of keeping our society and its members productive; we need these things to survive. Here we find the support structure for every culture. It is also where the rats race. These are the everyday affairs of "man."
Poetry, I believe, is a matter of the heart and mind because it requires us to assume responsibilities to ourselves. If we write poetry, we try to bridge the disconnect between the world-at-large and matters of the heart. The poet speaks out: but it does not need to always be sober or tragic; poetry can be uplifting, enlightening or funny. We need only be honest with ourselves as poets, and the work will speak its own truth.
With poetry how can there be mistakes? It is very forgiving. The poem, like any piece of art, speaks to each member of its audience in a different way. When it leaves its "creator," it becomes a new entity that draws its identity from the specific and personal response of each person who experiences it, with his or her own collection of personal experiences at hand. We are given flexibility to explore, to report and to be praised or misunderstood.
It is interesting that in the quote, poetry is placed on the same level as medicine, law, business and engineering. It is described as something with a substantive purpose, and the speaker insists that "cute" isn't it. However, poetry is defined by the presence of "passion." This reminds us what fire and energy may be found in verse.
And whether we read or write poetry, its power is obvious to us and others. When we write poetry, we inspire others with what we feel deeply about. When we read poetry, we acknowledge and validate the author's work: whether we agree with it or not. We choose to examine and evaluate, and these are the things that the poet searches for: not acceptance, but attention and consideration.
We read and write poetry because of our heart's passion. And rather than be categorized with the more serious aspects of the precise world of engineering or business that "sustain life," poetry is placed with beauty, romance and love: they are the things that guide us, feed us. Poetry can speak of beauty, love and romance where nothing else may, but it also feeds the spirit within, and keeps it alive.
Literally, poetry is verse often written in meter, with rhyme and other literary devices to give it a musical sound. Poetry catches the ear, and is best read aloud. And It is amazing that poetry can speak so many ways to so many different people.
Poetry may not serve the sole purpose of being fun, though often it is, but it allows us to express and connect in a way that can lift us up, help us to better know ourselves and our world, and provide the foundations for the more serious, sometimes less pleasurable aspects of life, such as business or work. It is the soul's "oasis." And it makes us whole, even while sometimes chopping us into pieces. It is the language of beautiful things that cannot easily be defined.
There are some things that are necessary in order to live. Poetry is something that is necessary to be alive.