Why do we have Mass facing the people?
No one knows for sure. Obviously there was some reason for almost every church in the Roman Rite to change the orientation of the priest at Mass. However, we can find no document that mandates this change. It has been said that Mass versus populumemphasizes more of the sacred meal aspect of the Mass. Also, some people claim that when the priest faces the people, he encourages participation by the laity. As noble as these goals are, they have not worked out as planned. The first one is based on a false dualism between sacred meal and sacrifice since both go together in the ancient world. The second one gravely misunderstands participation to be the activity of the lay people instead of a deepening in prayer. The goal of the Mass is not just to increase the verbal responses of the faithful, but the lead them to know, love and serve God in their prayers. My personal theory on why versus populumMass became the norm in the Ordinary Form is that during the Vatican II people would watch Mass in St. Peter's on their TVs. When they saw the Pope celebrating Mass versus populum, they assumed he was trying to show the proper way to celebrate Mass for the whole Church.