Agreed. More data is needed to see clearly if on a larger scale this is economically feasible to do. From my little experience with hydroponics, water and land use are the two major wins. Electricity can be a deal breaker but that depends on a lot of factors (type of produce, electricity prices, closeness to city, production vs consumption quantities, etc).

From a personal point of view, I strongly support this type of growth for a couple of reasons: more food for less cost, cities gain food independence, natural land use and abuse gets curtailed dramatically. Now if we could only switch more people (me included) to a vegetarian diet.