If you believe that the poet's emotions are the subject of a poem, you are likely to emphasize, even overemphasize, the typicality of poems dealing explicitly with es., such as Shakespeare's sonnets, Coleridge's Dejection, and even (as in the case of many romantic critics) lyric poetry in general. If on the other hand you regard e. as merely the fuel, you have to deal with the fact that the writing of philosophy, psychology, even mathematics may often be fueled by e. The romantic doctrine of the presence of the writer's e. as not merely external cause but in some way intrinsic to the product at least had the advantage that it provided a criterion for distinguishing poetry (more generally, imaginative lit.) from other forms of writing.--New Princeton Encyclopedia of Poetry and Poetics, entry for "Emotion"
I think a corollary to the romantic overemphasis of the lyric mode and mood is often, among those who mistake emotion (as opposed to language) for the medium of poetic art, is the reliance on bald statements of feeling as vessels for emotional content. Such direct statements are usually--tho by no means always; timing is everything--oddly ineffective means of jumping the emotional spark-gap between poem and reader--unless the reader is preternaturally empathic. Far more effective, in my experience, are the cold tools of a poet's trade: image, metaphor, rhythm, various forms of rhyme, etc. To say nothing of the weight of what isn't said.