Why Benedict's first two encyclicals are on love and hope

The answer to this question is found in an earlier post: Benedict's main point in his book, Jesus of Nazareth.

"What did Jesus actually bring, if not world peace, universal prosperity, and a better world? The answer is very simple: God. He has brought God... He has brought God, and now we know his face, now we can call upon him. Now we know the path that we human beings have to take in this world. Jesus has brought God and with God the truth about our origin and destiny: faith, hope, and love."

The importance of "faith, hope and love" was already emphasized by then Cardinal Ratzinger in his book God and the World. There he quotes Sor Lucia on the only message that is important, the real message of Fatima. Sor Lucia told him to tell the world this: Don't take notice of the other things related to the Fatima story. The only message that is important is "faith, hope and love."