The following excerpt is taken from SACRED THEN AND SACRED NOW - THE RETURN OF THE OLD LATIN MASS by Thomas Woods, Jr., Roman Catholic Books, www.booksforcatholics.com, Copytright 2008. (My emphases and comments appear in bold type.)
Important Features of the Extraordinary Form: Eucharistic Ministers Not Used
In the extraordinary form, the distribution of Holy Communion is confined to the ordained priest (or, in rare cases, to deacons who are on their way to becoming priests). Lay ministers of the Eucharist are not used.
This aspect will no doubt seem jarring to those who have grown accustomed to the sight of laymen flocking into the sanctuary in order to function as "Eucharistic ministers." But for one thing, this practice was supposed to be rare even in the ordinary form of the Mass-hence the official title "extraordinary [in the sense of unusual] ministers of the Eucharist." More importantly, the beautiful practice of receiving Holy Communion at the hands of a priest plays an important role in reinforcing priestly identity and gives meaning to the discipline of celibacy observed throughout the Roman Rite.
Father James McLucas, former Christendom College chaplain and a priest of the Archdiocese of New York, wrote an extended and important reflection on this subject in 1998. The celibate Catholic priest, who gives up the holy estate of marriage and an exclusive relationship with an earthly spouse in order to devote himself to God's service, was traditionally consoled by an exclusive relationship of his own; he alone could touch God." The traditional role of the celibate priest as the sole administrator of the sacred, "Fr. McLucas explained, "assisted him in sublimating his natural desire for exclusivity with another in marriage, and preserved his orientation toward his spiritual espousal to the Church and his spiritual fatherhood." (10)
The priest does not lose his normal human need for an exclusive relationship with another simply because he is a priest. But while other people satisfy this need through marriage, the priest finds it in his exclusive custodianship of the Eucharist-"an incomparable and unparalleled intimacy", with God, as Fr. McLucas put it. When laymen touch the Host, they (unwittingly, no doubt) deprive him of this exclusivity, which is supposed to ground and give strength to his celibate commitment.
Furthermore, the paternal dimension of the priesthood-the priest's role as spiritual father-is undermined when the priest is in effect told that after the consecration he is really no longer needed; the laity can take things from there. "The act of the priest 'feeding' the faithful with the Bread of Life incarnates his role as Its sole provider and, far more than the eye cans see, forms his and his people's perception of his spiritual fatherhood," wrote Fr. McLucas. And young boys are less likely to pursue priestly vocations, or indeed to be intrigued by and attracted to the priestly office in the first place, if the priest is not a figure of awe, who alone brings his people the divine gifts. If Mrs. Jones can do practically everything he can, young men will be less likely to be willing to make the sacrifices associated with the priesthood.
(10) This section is deeply indebted to an extraordinary article: Fr. James McLucas, "The Emasculation of the Priesthood," The Latin Mass, Spring 1998, available at http??www.latinmasmagaizne.com/articles/articles_emasculation.html