As with so many subjects, it seems to come down to two sides pretty mush trying to court the squishy middle to tip the balance in their favor. Tax revenue is usually one of the arguements used by the pro-weed bunch. I assume that legal cultivation would increase revenue on one end(selling cloned plants in dispensaries), and potentially undercut it on the other end(reduced consumption of State-grown weed.)
Seems like someone would work up some enthusiasm for an initiative petition. ( Irony noted.)
Washington is a state that has looked the other way on marijuana my entire life. There were head shops 50 years ago when I was a teenager. We have had legal medical marijuana for nearly 25 years.
There is simply so much marijuana available and so many people are growing it themselves without any fear of prosecution that they just expect it to be legal. My guess is that the people making big bucks will see this as a threat to some of their ill-gotten gain and keep growing at home illegal if they can.
I am sure that you realize that Alaska has allowed people to grow their own since 1975. This lowered the profitability to the point that no one bothered to push for legalizing sales until 2014.
https://www.washingtonpost.com/news/wonk/wp/2014/09/24/alaska-legalized-weed-39-years-ago-wait-what/
You don't need much space or expensive equipment to grow marijuana.