Its all stupid, its like arguing whether its better to shit boxers or shit briefs, you're still shitting yourself. As a Canadian, I can tell you that all legalization did up here was ostracize the stoners. Just because getting baked is now legal, doesn't mean anyone wants to put up with shitty stoner activities, it rapidly lost its luster for most folks. Most of the weed shops have long since closed, because it turns out most supposed stoners were just scene kids doing it rarely cuz it was cool and edgy, and now that its something a 40 year old accountant is doing, they don't want it anymore.
The only thing its been destructive to is the retards who decided to drive high, and lets be honest, they'd just reach for the bottle instead. Drugs don't make retards, they just enable 'em. Not that Jack could process that complex order of events.