While I don't share your opinions on marijuana, I do have negative feelings about some more harmful drugs. However I still don't want to lock people in a cage for decades should they choose to ingest them. Nor do I think the good done through "sending a message" by doing so would outweigh the injustice and cost of the law itself.

But keep in mind I'm a libertarian, and I generally support locking people in cages in fewer circumstances than the average member of the population.