I don't really understand the fuss around Cannabis based medicine considering how frequently we use Opiates to treat other conditions. Drugs can be both harmful and helpful. Personally I view Cannabis as far less damaging than alcohol, I've used it from time to time and the fact it's illegal is laughable for what is basically a mild relaxant
Opiates and opiods are well studied, used medically in a pure form and controlled as tightly as is possible in most places. Despite that, they're widely used recreationally and kill a lot of people as a result, also blighting the lives of many more who survive.
Cannabinoids are not well studied and cannabis is an extremely widely varying mixture of chemicals. The effects of some of those chemicals are hardly known. The effects of variations in the proportions of the chemicals are hardly known but what evidence does exist implies that variations in the proportions can result in very different effects even at the same overall dose.
Seperating out medicinal use and recreational use is not realistic. It's never worked anywhere else, so why would it work here? Besides, the idea of "medicinal use" is little more than a tactic used by people lobbying for legal recreational use and people lobbying to be allowed to sell snake oil for their own profit.
The use of properly tested and properly regulated cannabinoid medication is one thing, but that's rarely what people are after and it would take years. Which cannabinoids? In what proportions? At what dosage? What are the contraindications? What are the effects, both beneficial and adverse? Some researchers and some drug companies are asking that question, but the "question" most campaigners are "asking" is "I want to get high now" or "I want to sell unregulated substances with unknown effects and profit wildly from my own untested claims and the hope and fear of other people".
The fact that you refer to cannabis as a single substance with a single mild effect shows that you're not well informed. There's a whole slew of different cannabis (cannabises?) that can have wildly varying effects and some of them are not mild at all. Psychosis, for example. There are also new types of cannabis being created all the time. It's not particularly difficult to do even if you don't have a properly equipped lab and the right knowledge. It can be done by nothing more than selective breeding. It's slower and less precise and more limited in scope, but it works.
That's one of the more rational and pragmatic arguments in favour of legalisation - if it's regulated then it would be possible to at least mostly control it to minimise the risks. If anyone really knew what the risks were and why. For example, there's some evidence that the proportion of THC to CBD is an important factor in the degree of risk, but it's far from proven and can't be without a far better understanding of how cannabinoids work or large scale clinical trials feeding different groups people with different doses and combinations to compare the groups over time. Which would be wildly unethical for a recreational drug.
I've used a variety of drugs recreationally, including cannabis. I don't regard it as being laughable that it's illegal. Debateable? yes. Counter-productive? Maybe. Laughable? Not at all.