The Gateway theory has been disproven repeatedly by several respectable scientists, it doesn't stick. The argument is that it should be legalized (beyond the fact that its harms are greatly exaggerated) is that because it is already very easily procurable virtually anywhere, why waste funds trying to stop the inevitable? Instead it could be taxed and regulated by the government, much like alcohol.

The Netherlands decriminalized it, and the country is not on its way to hell. In fact, according to reports the amounts of hard drug abuse have dropped slightly since decriminalization. And they tax the hell out of it...