Not being ironic or sarcastic here, not even defending your president's answer, just an honest question: is marijuana really proved to be totally non-addictive? Or is it something still up for debate and research?
Marijuana is addictive in the same manner as is enjoying a scone with your tea every morning. Once you are accustomed to that scone, if it's taken away you experience an annoyance that slightly disrupts your mental well being. How disruptive is not having that joint after work? Not enough to measure. Physical addiction? LOL. There is none. Even government studies have refuted that theory.
As for the rest of the letter's statements, well, charitably, it was well written. It was all lies and 1930's-style FUD (a la "Reefer Madness").
It is in Obama's best interest to lie his way out of having any serious discussion on the legalization issue because he knows that he'll have his ass handed to him in a debate on the subject. He has no ammunition and no way to find any because it doesn't exist unless he has it manufactured.
Perhaps Michelle or one of his kids will be stricken with Multiple Sclerosis. It would be a very Dickens-esque ending.