For me the smoking issue is one of a health concern. I am very allergic to it, instant migraine, runny nose, rash that seems to be getting worse and worse as I get older. So I need to avoid it altogether. I have been on another cruise line(Celebrity) and my experience with it was bad when it came to smoking. The casino was central on the ship and near the grand foyer and I could smell the smoke anywhere near the center of the ship because it wafted up. I know most people who are not sensitive to the smoke can not smell it but I have the nose of a bloodhound on top of being allergic to it. I actually have this https://en.wikipedia.org/wiki/Hyperosmia, it sucks. That ship also allowed smoking at almost all of the outdoor bar areas which were around to pool decks. So that limited me greatly on where I could actually go on the ship. The Disney cruise line keeps it to 1 side of the ship away from the main pool areas so I can avoid it. And most gamblers are smokers, just go to a casino and look around. For me the Disney cruise is amazing, not for the smoking issue but just in general. The food is amazing, our room has always been spotless, the bed is comfy, and the customer service is outstanding. I believe that you get what you pay for when it comes to cruises.
And all ships are different, I have been on ones where the casions are easy to avoid, and inless you are next to them, there is no smoke.
Honestly, I cant stand cigarette smoke either, but I am not allergic to it. I will leave an area if it is too smoky, including a casino.
DCL is a great cruise line for the reasons you list, but not so much greater in those areas to justive the outrageous prices they charge.