I'm not disagreeing with any of what you said but just because cannabis is natural it doesn't mean it's safer than any medication out there - Opium is natural and comes from a plant but it definitely isn't safe to consume as you please. There are other toxic natural plants. Also, the Caffeine in Coffee CAN be bad for you (large amounts have been linked to cardiac arrhythmia) and is known to be addictive. Nicotine is natural and is addictive and can be extremely toxic.

As I said: I'm not disagreeing with anything you've said and neither am I saying that Cannabis is harmful but the fact that it's a naturally occurring substance is a poor argument for it being okay to consume.