I've been thinking along those lines myself, Aurons Ghost, and I agree that there aren't too many locations suitable for living in Spira. (Or, at least, the parts of Spira that we see). Of course, they could chop down the Kilika Forest and the Macalania Forest, although I doubt they'd do that - at least not the latter one. I don't think Spirans are as cynical as us.
But I thought the inlands ruins scattered around Spira were broken partly because of the great war and partly because they weren't used anymore due to the teachings, and therefore they were left to the tender mercy of the passing of time...