This is a very sophisticated question. I think what you are getting at is the idea that form is a conveyor of meaning as much as the content. In this way, the literary elements speak of the the world as much as what is actually written. So, if a literary piece is about war and the atrocities of war, then the literary devices can add to the horror of war. For example, the work can use metaphors that speak of death or use symbolisms that speak of horror. All of these can be every effective in getting our emotion involved. In fact, it can be more powerful than words.
In light of this, a work with literary elements that add to the theme will make that work deeper. It will give it a dimension that words cannot.