When I read your first line, as displayed in the forum list, I wanted to say that Shakespeare might agree with you. But when I read your post in its entirety, I changed my mind.
I do agree that the crafting of a poem is never careless, although some have famously created under the influence of mind-altering substances.
I've heard it said that King Lear is the greatest love poem ever written, and there's surely an abundance of "spontaneous and unrefined" language.
To me, the difference lies in the art of the poem, which may be experienced on many levels. Poetry makes use of the connotative meanings of words - meanings you don't find in the dictionary.