The USA continues to classify marijuana as an illegal drug.  Because of the peculiar US federal system and SCOTUS decisions on treaty implementation, states can act unilaterally.  That does not apply in Canada as illegality of drugs is an exclusive matter for Parliament.

Portugal, Mexico and the Netherlands have not legalized marijuana - they are decriminalization regimes.  As the task force notes the only country that has done so is Uruguay.  And as numerous studies and articles note the policy has been pretty much a disaster.
http://foreignpolicy.com/2016/03/21/uruguay-marijuana-legalization/

And the argument crime is reduced and fewer prosecutions? 

"While in 2013 (the year before cannabis legalization) 739 persons were indicted for drug-related crimes, in 2015 that number raised to 1233. Cannabis is still by far the most seized drug, with 2015 being the historical record."

And Canada is not Uruguay - we take treaties seriously.