As for myself, and not to be presumptuous, but I believe I'm understanding WildCat's position, the hypothetical we're describing is post-prohibition. With marijuana being illegal, people risk having their homes and property confiscated for growing it at home, so of course they want to get the maximum yield from the smallest possible area. But if risk of losing one's property isn't an issue, they won't care if they dedicate a few extra square feet to the pot garden. Not if it makes the pot almost free. Yes, we can grow high yield, pest free, consistently sized tomatoes (marijuana, cucumbers, etc.) in a climate and light controlled indoor hydroponic garden. But we can also grow excellent marijuana in most parts of North America without all the accoutrements.
And more to the point, if the taxes on commercial weed are so high that consumers are uncomfortable paying for it, and/or if permits and fees cost so much that commercial producers have to charge exorbitant prices, lots of people will likely grown their own. We're talking about mainstream users, tens of millions of them, not the small percentage of connoisseurs and hardcore stoners. The average guy won't care about maximizing gain any more than he worries about maximizing his cucumber crop. Even without lights, pumps, vats, and timers, regular people who just want a decent product for very little cost, time, and effort, will happily grow a year's supply in a corner of their backyard. And without even trying they'll often have enough to give a few ounces to some friends and relatives.