The hermeneutics of liturgical fittigness: ad orientem - versus populum

I would like to resume our discussion of the sacramental hermeneutics of fittingness in the changes in the Roman liturgy since Vatican II. So far we have explored four issues: (1) posture: "On the sacramental hermeneutics of fittingness in posture for prayer" (March 2, 2006), which was primarily concerned with the question of which posture was more expressive of a proper disposition for penitential prayer; (2) mode of reception of Communion: "On the hermeneutics of fittingness: Communion in the hand, standing" (March 6, 2006); (3) the Communion rail: "On the hermeneutics of fittingness: the removal of the Communion rail?" (March 22, 2006); and (4) the veil: "The hermeneutics of fittingness: head coverings for women" (April 8, 2006).

In this post I would like to entertain the controversial question of the orientation of the priest during Mass: ad orientem (facing "towards the Lord" together with the people), or versus populum (facing the people). Since the Second Vatican Council, as is transparently obvious to anyone who has set foot inside a contemporary Catholic church of the new liturgical missa normativa, the priest faces the congregation throughout the entire liturgy. Today it is surprising to most Catholics who visit many Lutheran churches to find the minister, at various points, "turn his back" to the congregation as he orients himself (or herself, in the case of some ELCA congregations) towards the Lord, according to ancient Catholic tradition.

In his Preface to U.M. Lang's book, Turning Towards the Lord: Orientation in Liturgical Prayer, the former Joseph Cardinal Ratzinger writes:

The Innsbruck liturgist Josef Andreas Jungmann, one of the architects of the Council's Constitution on the Sacred Liturgy, was from the, very beginning resolutely opposed to the polemical catchphrase that previously the priest celebrated 'with his back to the people'; he emphasised that what was at issue was not the priest turning away from the people, but, on the contrary, his facing the same direction as the people. The Liturgy of the Word has the character of proclamation and dialogue, to which address and response can rightly belong. But in the Liturgy of the Eucharist the priest leads the people in prayer and is turned, together with the people, towards the Lord. For this reason, Jungmann argued, the common direction of priest and people is intrinsically fitting and proper to the liturgical action. Louis Bouyer (like Jungmann, one of the Council's leading liturgists) and Klaus Gainber have each in his own way taken up the same question. Despite their great reputations, they were unable to make their voices heard at first, so strong was the tendency to stress the communality of the liturgical celebration and to regard therefore the face-to-face position of priest and people as absolutely necessary.

What rationales have you heard for the changes since Vatican II in favor of the priest facing the people? There must be some, surely, though whether they are good rationales is another question altogether. I know many good priests who speak with apparent gratitude of the change to versus populum, including not only my own priest, but Preacher to the Papal Household under Pope John Paul II, Fr. Raniero Cantalamessa, whom I heard allude to this issue during a speech he gave at the Eucharistic Congress in Charlotte last year. Yet, for the life of me, I have not yet heard a clear or cogent rationale given that makes much sense to me. Ratzinger himself, on the other hand, offers some plausible arguments in behalf of the ancient ad orientem tradition. Which is the more fitting orientation, and why? What think ye?