i'm not surprised by this; it seems like pei is the exception, and probably because it's an island. alberta likely levels out in a month or two, too.
first, you have to take into account the "fad" aspect of it. i would bet that the actual reality is that a lot of people tried it and realized it's really not such a trip, after all.
second, from what i can tell it's simply too expensive.
if the premise was to legalize in order to fight organized crime - something i initially thought was just an excuse but am starting to believe the government might actually take seriously - then this was a solution seeking a problem. marijuana isn't addictive. what that means is that the cartels don't have time for it. i'm sure that some amount of pot moves with the cocaine and the meth and the heroin, but the overwhelming amount of marijuana in canada is produced and sold by mom + pop growers. until the system reflects this reality, legalization is going to be a flop.
but, at least the cops aren't bugging you if you're smoking in the park, right? well, except to write you a ticket.