Personification

An interesting style of Emily Dickinson's is to personify the actors in her poems. Thus the actors transcend noun-itude and become beings in the sense I am a being, or you. However, a middle schooler could make that obervation. My question is why? and what affect does it have on the poems' meanings?

Let's look at The Clouds their Backs together laid. We have the proper nouns Clouds, Backs, North, Forests, Lightning, Thunder, Tombs, and Temper (I'm assuming Nature is already a being). Reading through the poem the first time, one understands the first six proper nouns are entities of a storm. Nature's Temper is said storm. Storm of vengeance in this case. Obvious stuff. Those are all capitalized to show their power and symbolism as extreme forces capable of change. Tombs is another story. "How good to be in Tombs" where the storm cannot reach. Tombs is the "savior". Dickinson is basically saying it is better to be dead than subjected to the anarchy of vengeance. That's the general gist of the poem I got. You are welcome to disagree.

However, back to the original question. I already answered why? (see above) as for the changing of meaning, I'm taking a shot in the dark. The word "mice" is not capitalized like all the other nouns (missile being an exception). This is to clarify the noun in its descriptive role. Could Clouds, North, Forests, and Lightning be people? Perhaps but what about Backs? Backs has no descriptive verb, whereas the others  behave with a rage-filled-scorned-lover type of vengeance when combined. This being said, is Dickinson just using literary tools to screw with us? Or does this personification change any of the poem's intent?