I fear that, unfortunately, a liberal approach to drugs will not end well at all. And I have thought a lot about this and heard all the arguments in favour. And yes, I know about how alcohol is legal and much worse than mj.
But suppose there was a drug even "better" than mj, legal, cheap, very available and had no side effects whatsoever. Suppose it was not addictive, just THE most pleasant thing you could do in your spare time. How would the society be affected by replacement of a complex system of drives and desires with one simple desire, to get high on this new drug whenever possible?
I fear we'd be facign the ultimate Tragedy of the Commons.