Smoking should be banned because it is known to give cancer to both the smokers AND non-smokers. Non-smokers can still get smokers lungs because of passive smoking. Also if you get a very ignorant smoker he will blow fumes right into your face which is not nice.
I hate smoking. It is repulsive to me, and it repulses me even more when I see what it does to some people. But just because it's disgusts people and may cause health problems, it doesn't mean we should ban it. People have a right to smoke if they want. Some find pleasure in it, and as long as people don't smoke where a bunch of people can inhale fumes, it's okay by me, besides the fact that it makes me sick when i see people who smoke.