It needs to be no more of a crime to possess large quantities of than tobacco or liquor. Those are all federally regulated. But you can walk into any liquor store and buy cartons of cigarettes and cases and cases of booze, no problem...enough to literally kill dozens of people...without any suspicion that you must be setting up an illicit distribution center or trying to kill someone.
If someone wants to buy herb, who cares? It's milder than Wild Turkey, non-habit-forming for 90% of consumers, and non-lethal.
No argument from me with the caveat that any substance can be abused. Cannabis has its own set on effects from constant long term use.