Absolutely not. Why shift a multibillion dollar industry from legitimate businesses to the black market? In addition to that I don't think the government should be telling people what they should be smoking or not smoking, though I do think they should make the associated risks as apparent as possible so that people appreciate what they are engaging in. And by risks I mean thoroughly investigated risks, not just "drugs are bad, mmmkay". Prohibition does not work and causes more harm than good. That being said I do not think any drug use that through its nature is a toxic contaminant to the local atmosphere, especially en masse, that affects more than the individual making the choice to consume, should be allowed in every place where people choose to socialize. Designated places to consume drugs (alcohol, tobacco, cannabis, etc) should exist, and combinatorial places as well (smoking bars/cannabis+tobacco bars, etc).
Smoking is an unhealthy, decadent, and antiquated practice; it feels pretty good though. But there exist ways to consume nicotine that do not have to involve other people. During the day people can always use nicotine gum or other products (I used to do this). I do think that if enough citizens ask there should be designated smoking areas in accessible places, that have at least a roof over the top for shelter, and during winter could have sheets of plastic set around to keep in the warmth (put a couple of little chimneys on the top to ventilate it). In tropical areas mosquito netting could be draped around it. Just to be clear I don't advocate banning it on the street or etc but I do think that people should show common courtesy and smoke in a discreet area. I always did this when I smoked, no matter the weather. I see a lot of smokers do this as well so I don't think that many have a problem with the idea, other than the die-hard pseudolibertarian style smokers who want to blow smoke in people's faces just to show that they can
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Opportunities multiply as they are seized. -Sun Tzu
Nature creates few men brave, industry and training makes many -Machiavelli
You can safely assume that you've created God in your own image when it turns out that God hates all the same people you do