as for responsible users that smoke in reasonable places like outside bars or concerts, or in recreational areas away from residential housing, it is better for us to keep it underground than to sell it in storefronts. if you ask around, that's actually a consensus position. most people support various decriminalization schemes rather than outright legalization.
you want to protect the marijuana plant from the drug industry, which will ruin it. that's what has happened in canada, where we now talk about Big Canna.