Doesn't kill 500,000 people a year.
Tobacco is by far, WAY more harmful than marijuana.
Relieves stress, is not responsible for peoples deaths (like tobacco is)
Although it can have harmful side effects to your brain after a long period of time and prolonged use, the 2nd and 3rd hand smoke aspect doesn't affect nearly as many people as Tobacco does. You won't die from smoking pure Marijuana, unlike Tobacco, which cuts 20 or up to 30 years off your life. Marijuana also doesn't harm the environment when smoked, unlike Tobacco. You also won't get numerous types of Cancer from Marijuana.
I would much rather humans use substances that do not effect their mental aptitude negatively. Tobacco, pure tobacco, is actually nowhere near as deadly as people make it out to be.
If you smoked cannabis in the same quantity and amount as smokers smoke tobacco you would be worse off quicker both mentally and physically. Cannabis has a lot more carcinogenic tar and aromatic hydrocarbons per ounce compared to tobacco. Tobacco does not have mental health problems associated with it.