Even Spain isn't nested like France. Do you go with political boundaries or cultural ones? You might as well just list the 40 DOs. Does the region of Catalunya really mean anything by encompassing Priorat and Penedes? I think it produces a false sense of information to do so.
Well, if you apply that logic, Andrew (and mind you, I'm not saying it's wrong), then France doesn't make any sense either.
If Catalunya, encompassing Priorato and the Penedes, produces a false sense of information, then what in the world does the "Loire" do, encompassing Muscadet, Chinon, Bourgeuil, Touraine, Vouvray, and Sancerre? Or the Sud Ouest, for goodness sake? What a hodgepodge that is, ranked perhaps because of proximity, but certainly for little else.
I am afraid that when it comes to wine, there are so many nits to be picked, and so many wits to pick the nits
that we'll none of us ever have a single consensus on nomenclature.
Anywhere wine is grown, trade groups (mercantile interests, including the growers, wine producers, real esate speculators, and politicians---who are a mercantile class of the highest order, simply tainted by hyprocisy and self-interest---will seek to twist the "rules" to their own devices. Thus chaos will come from order.
And all of us will then seek to impose a hierarchy on the chaos---to try to make sense of it all. Some people will care; others won't. And as soon as we have a relatively well understood and agreed upon hierarchy....well, someone will come along and do something that confuses it again.