Substances that cause health issues, and that are used in food distributed nationally, or even globally, are way more of a concern than recreational drugs.
Except the health issues caused by most recreational drugs such as Marijuana, Cocaine, Acid, Alcohol and Crystal Meth have far more damaging effects on a person's health and mental capabilities than those food additives.
Have you read some studies on the medical uses for that though? Recreational use is a bit over the line but the potential in medical marijuana is enormous.
I remember reading a story a few months ago about a person who had a serious problem with frequent seizures or something like that, but started ingesting marijuana and apparently it significantly reduced the number of seizures they had every day. So yes, marijuana use can be used for positive effects.
However it appears to me that in most cases where Marijuana is consumed, it is done so merely for "recreation", rather than to help with serious medical problems. It is also contributing to a decline in the productivity and acuity of some american jobs, and damaging the quality of services and business function.
On another note, when it comes to people without some chronic illness but to those who are merely bored or frustrated/anxious, the "beneficial" effects of Marijuana are something that can be better achieved through more natural means. Marijuana is, in such circumstances, unneeded, as the mind-altering chemicals in it are actually crude substitutes for natural bodily chemicals/hormones that are naturally released and recepted through normal healthy activities such as excersizing, socializing, and eating and sleeping properly. Doing these things can give you the same beneficial effect as marijuana but without the added health risks of memory impariment, disorientation, increased risk of heart attack, and inhibited brain development. In fact doing those natural activities creates the exact opposite of the harmful effects of marijuana: They improve memory, increase balance and dexterity, decrease heart attack risk, and promote brain growth.
Granted, Marijuana is still not as harmful as alcohol and other drugs, but it is still a harmful substance that has no business making our lives more negatively dependent and habitual. I for one wish no one here to spend their lives pumping their bodies full of such drugs. There is almost always a much better altenative to Marijuana.