Poetry is real. Real people have written it to express real emotion that is normally hidden. Poets write to show that people have felt certain things before which someone else may be experiencing at another time. A poem allows you to see beyond the surface. Sometimes this is done through metaphors or other abstract ways which cause you to really think.
Beauty is expressed, and art is emphasized through poetry. Finding and using words to fit exactly how you want them to takes time and thought. When people read poetry, they have a chance to really see the world with some of the bells and whistles stripped away; it lets them concentrate on the details which remain. Poems often describe life and illuminate aspects of it using flashes of imagery.
Throughout history, poetry has been important because it gives us a historical representation of what previous generations found beautiful, important, or profound. It can show us words and concepts from the past. Poetry can even depict historical events. Poets in the past may have written a poem after a big event had occurred (for example, WWII), and by reading their poems, we can see how the event affected everyday people.
Overall, I think poetry is important because it tries to render things that aren't easy to express in words. It does this by making use of attributes of language which aren’t commonly seen to instill deep thought and contemplation. In a sense, poetry uses words as doors to many possibilities. It carries our imaginations or stirs new dreams. Mainly, it extends the power of words to communicate.