First, reread the article and the post. This is not about smoked marijuana; it is about cannabinoids, the active agents in marijuana that bind with the cannabinoid receptors in the central and peripheral nervous systems. These receptors have many important roles in pain perception, anxiety and anger pathways, hormonal stress response, hormonal reproduction modulation, and others. The research is important for new treatments such as the one described for cardiac benefits of weight and smoking control.
Second - be careful with the word "never" in medicine and physiology. Marijuana has a long history as a medicine. For instance, the cannibis plant has been used in antiquity in many cultures for pain control. Chinese Emperor Shen Nung's Digest of Herbal Medicine, 2737 BC, lists cannabis as a treatment for digestive disfunctions and maladies now thought to be related to tumor growths. The Greeks and Romans listed it as a medicine for pain and seizures. Serious research began in the 1800's. In 1830's, there were published papers regarding the use of cannibus as an analgesic, anti-spasmodic, and muscle relaxant. Medical papers of the late 1800's and early 1900's listed cannabis as an effective treatment for tetanus, neuralgia, analgesia for persistent pain, uterine hemmorhage, and to relieve withdrawal symptoms of alcoholics. The banning of marijuana in the US stopped research into cannabis derivatives.
Then in the late 1960's, delta-9THC was found to be a powerful anti-epileptic. The FDA was pressured into considering the merits of cannabinoid research. In 1985, dronabinol was approved for the use of allieving the side-effects of chemotherapy and later, the use as an appetite stimulant for anorexia and AIDS therapy. Nabilone was then approved for similar uses. Research into cannabinoids was grudgingly allowed to continue. That lasted until the the end of the G.H.W. Bush administration and the beginning of the Clinton administration when cannabinoid research was again suppressed by the new War on Drugs efforts. Further research was left to less capable and less funded facilities in France, Germany, and Israel. Luckily, it looks like they have been able to produce some good results.
Smoked marijuana difficulties lay in dosage control and lack of purity of the active substances - not basic effectiveness. This is why the research on synthesized agents is necessary.
Also, until cannabinoids were researched with modern understandings of physiology. We were not aware that there is an endogenous cannabinoid pathway system and naturally occurring cannabinoid receptors in the body. Opium research resulted in our understanding the opioid systems in the brain and the mechanism of pain reception in the periphery. Without that, analgesics above the level of aspirin would not be possible. The cannabinoid receptors will have an even wider impact.