That's what I was wondering. I don't mean to get too out in the weeds, but isn't it psychological, since you can get the nicotine from vaping? If so, maybe the benefits to the 95%+ of the passengers who don't smoke may be worth the complaints.
I'm not one of those high-horse people. I was around it a lot growing up and don't make any moral judgments about those who choose to smoke. I just really dislike the smell and have had to go in from my verandah multiple times because of it. If that could be prevented better, I wouldn't complain about a spot up top to smoke.
On a side note, the very first cruise I took as a teenager, I somehow got talked into smuggling my older brother's cigarettes' on board. He panicked at the last second and, for some reason that escapes me now, decided it would be less concerning if I was the one caught with them.