I was really only addressing the notion that vertical farming took up more land. If we have as much extra land as you say, the point is irrelevant anyway.
But you need to remember that there are real costs to industrial farming on land. The use of pesticides, fertilizers and topsoil loss. There are a lot of benefits to vertical farming if it can be made to work economically.
Well, the primary costs today are water and labor. Fertilizers and such don't really cost much, which is why we always just overfertilize and now are causing runoff problems.
But you need to remember that there are real costs to industrial farming on land. The use of pesticides, fertilizers and topsoil loss. There are a lot of benefits to vertical farming if it can be made to work economically.