Maybe there are two applications of antiphonal singing. The side-to-side antiphony of Morning Prayer in our parish nowadays is what I experienced for years "in the Brothers," when not one of us was ordained.  I probably would dislike more singing in the fashion of the Responsorial Psalm, if that is what Archbishop Sample is proposing.  In some long-ago course on the liturgy, I picked up the notion that what we do in the Responsorial Psalm resulted from  the text of the psalm not being in the hands of the congregation or that the faithful were so unlettered that they had only to repeat their leader.