ideally policy would be to let it be legal to grow in small amounts but illegal to sell without a license and heavy tax
I think that's exactly where we will be come Jan 1 if I understand all the laws. But again, if the tax is too high, then it becomes worth it to produce "home brew" at scale without a license and sell illegally.
Maybe a better policy would have been a very high tax, but implemented in tiers over 10 years. Five years where you have low tax and give growers a chance to get up to scale and drop prices slightly overall so that it would undercut criminal growers, and then once you've destroyed the criminal infrastructure, you ratchet the price up for the social benefit.
Meanwhile, though, if you listen to some of the chatter out of Humboldt County, they are worried that legalization will put "mom and pop" illegal growers out of business.
I forget who said "No problem is so simple that, when looked at long enough, it does not become extremely complex."