Larison thinks proponents of marijuana legalization are being counterproductive:

...the standard “I’m in favor of legalization, and I’m the farthest thing in the world from a pot smoker!” argument ends up making the argument for legalization less compelling. This is because this kind of argument unintentionally reproduces the stigma against the drug and effectively endorses one of the key claims that supporters of criminalization make.

But anyone who does not fit the stereotype - and I have nothing but regard for stoners myself - is rendered invisible by the criminalization.