The papacy has always been influenced by church politics. Certain popes have been strong willed and others have been content to let the bishops run the show. I think that there are some tough fights and some rocky roads ahead for the church and maybe he felt that he wasn't strong enough to see the coming battles through to their end. I wouldn't want to tackle some of those problems at 55, much less 85.
Donít tell the Lord how big the problem is, tell the problem how big the Lord is.