When I said bow and stern smoking, I was talking about the far forward (and far rearward) side smoking areas, not the very front (bow) or very rear (stern) of the ship. It's hard enough to open those front facing exterior doors because of the wind. They even close off those doors when it's real windy.
I believe the drifting smoke from the forward side smoking areas affected a lot of balconies, causing the smoking area to be moved towards the rear of the ship where far fewer balconies would be affected.