Yes, they should. It would be irresponsible if they didn't. Government has the obligation to protect its citizens.
We don't have vigilantes patrolling our neighborhood. We don't organize posses. We don't hang criminals from trees. We don't make our individual rules.
We are governed by the rule of law. And the law is that medical marijuana is illegal. Change the law. Prove that smoked marijuana is medicine.
Interesting. The law will eventually change. Until then, tens of millions of people will still use drugs, illegal or not.