Many liturgical issues can be argued sensibly both pro and con. However, the one argument I have never understood has to do with ad orientem posture. How can it be reasonably claimed that the versus populum posture is less "clerical" than the ad orientem posture?
In very few situations in life do we accept a single person facing a group for any length of time. A speech, a toast--we accept these for a limited amount of time, and we are very much aware of the discomfort that accompanies an excess of the normally accepted limits. A conductor can face his or her musicians at length, yet consider the ceremonies that are accorded him or her, in order to justify such an unusual position. An actor or entertainer can face the audience, but only for as long as we really find her or him entertaining, and this is never very long.
Consider how odd it would be, among a group engaged in watching tv or any other group activity, for one of their number to adopt a position facing the group, instead of the tv. It would take just a minute or two before increasingly insistent invitations to sit somewhere else would begin to be offered.
In daily life, the one kind of person who is allowed many hours of steady versus populum posture is a school teacher, and for many students, these hours seem interminable.
For the people as well as the priest, Mass versus populum is an unnusual and unnatural posture. It feels uncomfortable. There is too much eye contact, and too many associations with school. Priests do not generally go into the seminary for the same reason actors go into the movie business. And the Liturgy is not a school--not like a normal school, anyways. The Mass is not a venue for one "expert" Christian to teach all the others, with certain exceptions, such as the homily, particularly that of the bishop.
The ad orientem posture softens the distinctions of roles; it does not accentuate them. By it we all spend nearly the entire Mass facing the same Lord, who really is so much greater than all of us that our separate roles for the sake of the building up of the Body of Christ have less opportunity to divide us.