1. The Holy Sacrifice of the Mass is experienced as having a theocentric direction and focus.I know there are those who consider it a shibboleth that some Trads, or crypto-Trads make too much of, but here's the way I think of it:
2. The faithful are spared the tiresome clerocentrism that has so overtaken the celebration of Holy Mass in the past forty years.
3. It has once again become evident that the Canon of the Mass (Prex Eucharistica) is addressed to the Father, by the priest, in the name of all.
4. The sacrificial character of the Mass is wonderfully expressed and affirmed.
5. Almost imperceptibly one discovers the rightness of praying silently at certain moments, of reciting certain parts of the Mass softly, and of cantillating others.
6. It affords the priest celebrant the boon of a holy modesty.
7. I find myself more and more identified with Christ, Eternal High Priest and Hostia perpetua, in the liturgy of the heavenly sanctuary, beyond the veil, before the Face of the Father.
8. During the Canon of the Mass I am graced with a profound recollection.
9. The people have become more reverent in their demeanour.
10. The entire celebration of Holy Mass has gained in reverence, attention, and devotion.
Is it necessary?
It is possible, to take on that list of rationales, for the people to remember that God is the center of the Mass; the priest to subsume his personality, to make it clear the Father is being addressed, to convey the reality of the Sacrifice, and to modulate his volume appropriately and meaningfully; and for all to be reverent and recollected; in a Mass celebrated versus populum.
It is possible.
But how frequently none of that occurs! You may say not all that often, (I would argue with you, but you may,) but even once is far too many times!
The ad orientem posture of the priest is a tool that can help all that happen.
If perfection has not been reached, WHY WOULD YOU DEPRIVE YOURSELVES OF THAT TOOL????
I cannot write a line of text without ruled paper without drifting up or meandering to the lower edge of the sheet.
Why would I want to do away with lined paper?
Do you paint, sew, bake, do carpentry? Some people can eyeball things, but most of us need to measure. What shame is there in that?
Because there are those rare actors who, sans costume, sans make-up, sans sets and lighting can BECOME SOMEONE ELSE, and not just transfix their audience but TRANSPORT them, to another place, another time - shall we do away with all the accoutrements of theatre?
Where does that leave the actors who are not Ralph Richardson, or Magda Olivero, or Anthony Hopkins? (Not to mention their audiences.)
Because my great-aunt Gen could feed a veritable banquet to a family of two dozen with a few cans, a loaf of bread, a wood stove, and a rare sort of genius, shall we sneer at those who need fresh food and a modern kitchen to even achieve "palatable"?
Yes, all the advantages derived from ad orientem can be achieved without.
But I have yet to learn of any advantage to versus populum.
Is there one?