Sorry for the smokers, but this trend will spread to more cruise lines. With the high rates of lung and breast cancer and local governments putting more and more taxes on cigarettes, smoking is not in a favored position.
It is up to you to do the research before booking with a cruise line if you are a smoker.
The other side of the coin, it is no fun to pay for a balcony and not be able to sit on it and enjoy it because smoke is blowing in your face. Remember that the fire on a Princess ship was the result of an ember igniting. Princess immediately changed the materials used on their balconies to those that would not combust and installed other preventive measures.
You may not see it as such, but the stricter inforcement of where cruisers can smoke on board, makes it safer for everyone. No one wants to experience a fire at sea due to a smoker's cigarette or an ember. Safety is the primary issue here -- not being unfair to any one group or singling them out.