Why? Why rood screens?

Simply, I suspect that the loss of Medieval church interiors could possibly be the greatest spiritual and cultural damage that Europe has suffered over the centuries.

I want to test that opinion. I want to get closer to a clear picture of the Medieval architects' vision. I want to clear away polemical clutter (Victorian, Puritan, Romantic, Anglo-catholic, Sarumite, Proto-orthodox, Anthropologist, Positivist, Nostalgist, Sentimentalist ...) from our modern view of the Medieval liturgical environment. I feel that if we let these creations speak for themselves we might learn something about our own faith.

Rood screens are tantalising in that, even though they must have utterly dominated every medieval nave large and small, it seems no specimens from major churches or cathedrals seem to have survived. Why are the all gone? They must have had something unique to say in defense of medieval spirituality! The only rood screens apparently to have survived are those in rural parish churches. Granted that many places considered rural now may have been quite metropolitan in the Medieval period (Northleach? Newark? Cromer? Boston? Rievaulx?), but the towering depiction of the crucifixion, the ornamental rood-screen-as-reredos, the rood-altar, the quasi-ikonostasis of saints and angelic portrayals - these must have been present in all our Cathedrals once, but no more.

Rood-screens are Britain's intriguing ecclesiastical ghost-story. I want to know more.