The other factor here is that there just isn't that much arable land in many places, so places that need to import food could instead grow their own using the facilities you mention here. For instance, here in Japan there really isn't much land for growing crops, for obvious reasons (plus there's a lot of typhoons which can be problematic for outdoor farming). But some big nuclear-powered hydroponic farms could very well be economically viable if the government provides some incentives because it wants to be more self-sufficient with food.