If we are to legalize weed, the government can tax the crap out of the growing and selling of recreational marijuana. Along with money, the side effects of pot are bad, but they are better than cigarettes. I personally do not smoke, but I do believe it would be good for the economy.
No. I do support the legalization of marijuana (as I do most controlled substances) because I take the libertarian view that what one does with one's own body is a personal choice. I also take the practical view that the so-called war on drugs has been a catastrophic failure. However, for the very same reason, I would oppose the ban of tobacco products.
From a medical perspective, marijuana is slightly less harmful than cigarettes (though by no means harmless), but it also has greater psychological effects (which is to say, I'd rather if someone near me smoked a cigarette while operating heavy machinery than marijuana).
Finally, I admit a personal thought, unrelated to politics: while I think criminalization of marijuana should end immediately, I hate the substance with a passion I usually reserve for the scientifically illiterate. I say this to make the point that I don't support its legalization just because I want to use it, but for a larger political reason.