What really upsets me about disfellowshipping someone for smokingis this: The reason there is a rule about smoking is because it's bad for one's health. We care about people and don't want them to harm their health. Fair enough.
However, the WTBTS just doesn't see how much more harmful disfellowshipping someone is to their psychological, and hence their physiological, self. The two are inexorably intertwined. When you cause someone the severe psychological and physical harm of disfellowshipping, it is so much more harmful to their mind, body and spirit than a few cigarettes could ever be. How much more loving it would be to show compassion for their struggle with a very strong habit.
People have killed themselves over the harshness of disfellowshipping. How is that any better than the long term risk of smoking?
True story: A long time poster on this board, who was very well known, and was once a bethel elder, said that he once pulled the body of a man out of a river who had killed himself because he was disfellowshipped for smoking. You can read about it here, Starfish, it is a JWD classic.