The bishops at Vatican II attempted to reemphasize the ancient, communal aspects of the Eucharist and Christ's presence. Today's liturgists and Church leaders believe that it is confusing to call for Christ to become present in the eucharistic prayer when the sacrament is already present on the altar in the tabernacle. It divides our attention.
When we are celebrating Mass, our attention should be devoted to the eucharistic action and all that it implies—not on the tabernacle.
Thus, the Church urges that the places of celebrating Mass and reserving the Blessed Sacrament be distinct, that the altar and tabernacle be separated architecturally and structurally.