Genesis 2:25 is not just a passing description of humankind before Genesis 3. It is drawing our attention to the emotional fulcrum around which the history of sin rotates, the fundamental source, harbinger and herald of what is to come. I would suggest that the writer wants us to pay attention to shame not just because it happens to show up later but because of its central role in all that ends in a curse. It is the emotional feature out of which all that we call sin emerges.