We avoid getting addicted for self-preservation if we can. I have my own Good Friday reading which places the sufferings of Christ not on some noble Anselmic mission but to identify with our anguish. See:
http://xianleft.blogspot.com/2005/03/blessed-good-friday.html

Suffering is good in that it shows us that we need to call out to God. Not from the egotism of "offering it up" but because most people are all too comfortable, especially economically and morally. Ironically, addiction brings people to that level of surrender to God that not even self-mortification promises.

As for St. John Paul's letter, I doubt it has gotteb anyone sober. It certainly would not have worked for me.