Meaning, in other words, that if marijuana was legal, its use would have no negative impact on society. Do you really believe that? Or do you wish to modify your statement?
There are health issues with chronic use. Respiratory, cardiovascular, endocrine, psychological, perhaps others. But, those problems will remain at roughly similar levels post decriminalization.
Enforcement of unenforceable laws is automatically arbitrary, and is the REAL danger to ALL freedom.
When the punishment for the use of a substance far exceeds its supposedly bad effects, it's time for people of logic to come together and change the law.