Yes, it should be. It has never killed anyone from an overdose, does not have any physically addictive qualities, and has pages worth of medicinal and commercial purposes.
Alas though, until recently I was under the impression that with this being the 21st century and all that we have moved past the "Refer Madness" propaganda of weed. But unfortunately, there are those who still believe weed is addictive, induces severe psychosis, and other things that real drugs, such as coke or meth or do. Now, while it may be true that more and more people are entering into rehab for weed, it must also be stated (which is conveniently not) that alot of people will voluntarily enter rehab for a reduced sentence. Even though this rehab can be something like AA or NA (of which marijuana is neither.)
For medical reasons, prescription drugs may have a better effect, but not one drug will do nearly as much as marijuana can. It also cost much less (unless you are buying very potent weed.) Also, it has many benefits that prescription or OTC drugs do not give. For one, pot induces the munchies. This can be used to treat anarexecs, and eating gives strength back to chemo patients. Marijuana also increases the effectivness of morphine, which means doctors could give smaller doses while the patient is recieving the maximum effect. People with Tourettes syndrome can also benefit from pot smoking, as it relieves muscle ticks.
And pot is NOT a gateway drug. It all comes down to personal choice. Some people are speed freaks, some pot heads, some meth heads, and some just drink. I've tried some other drugs, didn't like the effects, and don't use them anymore. It's as easy as that. And since nothing else is even similiar to pot, it's very difficult for it to be a gateway drug. Especially since a very large number of pot heads just smoke pot. It would be more fair to say that cough syrup is a gateway drug into psychodelic drugs, or ephedrine is a gateway drug into speeds. Both are legal, and have illegal drugs with similiar effects.