A large reason that there is a lot of pushback on fully legalizing marijuana is that the State is going to lose a significant revenue stream from the money that is seized in criminal marijuana cases. In my experience, when police make an arrest for non-civil violation marijuana, they seize any cash that the defendant has and since they do such a bang up job of explaining the timeframe for contesting the forfeiture of property, the money is deemed forfeited by procedural default (i.e. property owner doesn't file Petition for Return of Seized Property within the 45 days of arrest as dictated by the Court's filing rules).
In any event, I know a lot of the folks that are behind this bill and they have been putting in a lot of effort on this front.