The reason they started going after dispensaries in LA is that law enforcement complained. When you're building a police state, you need law enforcement on your side. Law enforcement, courts, defense lawyers, and the prison industry LOVE keeping marijuana illegal. It keeps them employed and in the money.
This experiment in CO will NOT work, because it won't be allowed to. The people can't be allowed to think they can vote for their own freedoms, what a terrible precedent for Obama and Holder.