Why do people always think that WoW-nerds have to be fat and ugly? Geez... You CAN play a lot of WoW and have a job and get out and everything. Goodness, you have to stop comparing a few extreme cases to someone who smokes a cigarette a day. Compare extreme WoW cases with people who smoke 5 packages of cigarettes a day at least; people who have skin like someone 20 years older than them, people who cough all day because of smoking and still won't stop doing it. And that's just the solo point of view. Throw those two guys, the nerd and the smoker in a room with others, and you get how their 'addiction' affects other people.
For me, I've been avoiding my smoking parents ever since I had reached an age that allowed me to avoid them. Because they never considered to not smoke anymore around me, not even when I needed medication due to asthmatic episodes. I practically flee from them again after having visited them for a few minutes these days because it's unbearable.
Smoking is worse than gaming because it affects those around you physically without them being able to do anything about it. You can't just stop inhaling the air around you. You can't tell your skin to not react to the smoke-saturated air. You can't tell your contact lenses to not start itching when you get smoke in your eyes. You can't tell your lung to not scream for clean air.
Oh and... I'll rather kiss the WoW-nerd than the smoker