The new bishop of Portsmouth, Philip Egan is speaking on the BBC. This bishop notes that the Pope has been very ill. He states that a bishop must be swift of foot and have drive.
I think illness and fatigue is the reason and we should not look farther than a courageous decision, although the Pope's days in a monastery also give us a great example.
Do not waste time. Do not spend time on things which do not bear fruit.
Pray.