So you doubt that God intends to draw great good out of illness. 

He either doesn't want to do it, or He can't do it, according to you. 

Which one of these alternatives do you believe?

Both are grave sins.

"Great good" could be:  tens of thousands of acts of (happily given) charity from her husband to his wife, or to their children.  

or it could be: reconciliation among family members, as sons/daughters, brothers/sisters draw closer to the dying person to help, to remember, to forgive, to ask for forgiveness.

or it could be 100 thousand acts of humility
or 150 thousands acts of abandonment. 

or it could be 200 hours of prayer...great intimacy with God. 

or it could be simply the smile that your wife gives to the hospice person.

Or it could simply be a husband who doesn't give in to despair. 

Who knows what God wants to draw out of our illnesses and death..but you must have faith that He can do it, if we have faith. 

That's not blather; that's our Catholic faith.