I'd say they'd want to focus more on the effects of the arrest rates going down. I think that is where you are going to see the biggest positive changes.
That said I think we still need to see marijuanna as a health danger. Much like smoking tobacco, long term irritation of your lungs is not a good thing. I hear a lot of people calling marijuanna a cure all and remember my grandmother telling me how she was told to start smoking as a cure to her anxiety. Not the same, but this was something she told me as I was watching her die slowly from a lifetime of smoking.