My conspiracy theory is that the money groups like it pseudo legal. It keeps prices high, so the people who greased politicians hands to get state restricted licenses get to make money hand over fist.
It's pseudo legal status is also great for politicians. Not only do they get this perpetual carrot to dangle over the electorate, they can milk money from both the Cannabis lobby and the Alcohol and Pharma lobbys by making promises to do slight tweaks to legislation.