This is good and humble. It is important on Maundy Thursday for the highest in the church to reach down to the lowest and wash their feet. It is a reminder of both lessons of Holy Week: (1) we are called to serve everyone including the low with our whole body and soul, and (2) everyone is guilty of the crucifiction.
Christ wasn't crucified by a small, conspiratorial cabal, but by the crowd and even his own apostles. Peter, that rock upon whom the church is built, abandoned and denied Christ. No matter how good we think we are, we are not good enough. No matter how much status we have in society, we are not good enough. We killed Christ. Our goodness, our status, our ordination will not save us. Only His mercy will save us. Will we recognize our utter unworthiness in time to submit with utter abandonment of status to His will? Pope Francis's decision reminds us that only utter abandonment of status followed by submission will save us.