There are huge benifits to the environment in legalization.
The syndicate growers would leave the forests and take their water diversions, pesticides and fertilizers with them.
People would not need to grow indoors greatly reducing the amount of energy being wasted by folks growing indoors just to hide it.
The smugglers would not be using fuel to bring marijuana across the border.
These are just a few of the benifits I can think of in addition to the myriad displayed above.

Time to end the prohibition.