The problem is that in the Middle Ages the territory under which the writ of the Church ran was universally and culturally, not just apparently, Catholic. That is increasingly untrue. A bad pope matters much more now than he did in 1455.
Considering the number of Catholic sects we have now as opposed to 1455, I think a bad pope matters less-not every Catholic walks in lockstep with the pope any more, and excommunication lost its sting centuries ago when it was overused-people figured out that the pope is human-and now the excommunicated person/persons would just go to one of the Orthodox churches, which makes excommunication ineffective. And only God can deny anyone salvation-not the pope or any leader of any other church.
People are less inclined to listen to a rogue pope-many of us know our history-and he is increasingly becoming irrelevant as anything but a tool for a communist/socialist political agenda...