All jokes aside, my hunch is that the pope may have recently received some bad medical news to the effect that his faculties will rapidly fail him.
There’s nothing cowardly, irresponsible or even unspiritual about a pope using his God-given intelligence, wisdom and discernment to reach the conclusion that his declining abilities would place an unfair burden on the church, particularly so soon after JPII’s difficult final years.
He decided that the best course of action was to leave while he was still in control of own decision-making process. For that he should be commended.
In doing so, he has taught a valuable lesson about pride versus humility.
And it takes a humble man to be able to walk away from a position like the papacy.
I agree with all you said. None of us have ever seen this happen before in our lives so it is unusual.