Pro:
+Less crime(Many violent crimes are related to drug deals gone wrong. Legalization opens the door to commercialization which means Marlboro Chronic will be cheaper than whatever little Timmy has to sell you, so little Timmy has no business.)
+Fewer broken homes(parents aren't in jail for enjoying some herb, nor are the children)
+Safer product(decriminalization leads to regulation)
+Economic recovery(decriminalization leads to regulation which means taxation)
Cons:
-Hemp would be a competitor
-Americans would be fatter and happier
-Everyone would know how to play the piano
Either way, people are going to smoke pot(which is less harmful than substances which are legal); they might as well do it in a way that helps the economy, the streets, and families.