I don't agree with harsh drug sentences either, especially for something as simple as possession. If a drug were involved in a situation where they were posing a great danger to the public via driving under the influence of said drug or in the case of an Assault charge or whatever, I would be a proponent of the drug's presence adding to the punishment, simply because it would ensure people are a bit more responsible about it.
People in CA can get up to 6 months in prison for a DUI alone, much less possession of Coke in addition to it.