Maybe this will help (and I've tried to restrict this to recreational drugs to simplify things). Legalization of marijuana should not be determined solely by a comparison to the risks of alcohol. In other words, just because marijuana may be "less risky" than alcohol is no reason to legalize it.
Furthermore, "risk" should play no part on whether or not a drug is legal. (Many legal prescription drugs are very "risky", and their usage has to be monitored closely).
So, in summary, risk is not a factor in determining the legality of a drug.
Now, once a drug has been declared legal, we can then consider risk. Very risky? Prescription or research only. Little or no risk? Over the counter. Anything in between can be handled by age restriction, quantity availability, licensing of distribution, etc.
"What do you consider the appropriate criteria?"
I have no desire to see marijuana legal. I used to feel that the arguments for medical marijuana and decriminalization had some merits. But the more I'm exposed to it, the more I see that these are just ploys towards eventual legalization. Nevada is a good case in point.
I have yet to see one good argument on why we should legalize (just) marijuana.
I have no desire to see marijuana legal.
If that's your answer, then basically it comes down to the only criteria that anyone should consider relevant is what you want.
Like I said, I never said you couldn't bring up the risk factors, you simply choose not to. And if risk factors are not a consideration, why did your duly elected representatives spend your money on research specifically to gauge what those factors are, for the purpose of determining legal status?