Smoking can be a nasty, addictive, hurtful habit. Very little, if anything, is positive about smoking. So should it be a disfellowshipping offense? If one is addicted, and doesn't take the steps to quit, then, probably they should, especially if they spend money on this habit that would take away from their family's necessities.. But if someone enjoys a cigar or pipe or the occasional cigarette and they aren't addicted and can control the habit, then what bible principle is being broken? The same is true for alcohol. If you can't control the addiction, then there are bible principles involved. If you are an occasional drinker with no addiction, then no problem. Same with over-eating. Gluttony and drunkeness are both condemned. Smoking, IMO, falls into the principles used for over-eating and over-drinking. We need food, but overeating or gluttony is wrong. We don't need alcoholic drinks, but in moderation they are allowed. We don't need tobacco, and the bible does not speak of it at all. So if we use the principles used for eating and drinking, then we can see that some could be able to enjoy a fine cigar or pipe, while others would need to avoid it completely so as not to become addicted.
This whole thing becomes more muddled up when you consider that the cigarette companies add additives to make cigarettes more addictive(and thus harmful).