Good point. And a third benefit I didn't think of in the first place: third-world governments not only often misprice water, but also can't effectively enforce

Good point. And a third benefit I didn't think of in the first place: third-world governments not only often misprice water, but also can't effectively enforce water access rights --- which often leads to violent conflict (between tribes with different modes of production, etc). Shifting food production towards richer economies would reduce the strain on water resources in the third world.