In the past, even the near past, smokers were tolerated by non-smokers and so smoking was allowed. But that is very quickly changing. We've seen the number of smoking areas go way down from literally half of the ship to now just the casino and one or two small outdoor areas.
Even with that, there are a lot of people who refuse to go to Vegas or a mass market cruise line because of the smoking. At a certain point, Carnival will be alienating more people by allowing smoking than by banning it. The question is where is that inflection point.