Each Sunday the first thing we do in church is to gather. As a Christian community we gather FOR each other. The first ritual we should experience therefore is a ritual of welcome, of courtesy, of hospitality. Just as all Christians are called to read God's Word (not just Lectors), and all are called to minister the Lord's real presence, (not just Ministers of Holy Communion), so all of us (not just ushers and greeters) are called to be ministers of hospitality. And like other ministries, there are special ministers of hospitality. They are very important.
Often an usher or greeter can set the tone of our readiness to experience God more than any other minister. They are usually the first to greet us when we arrive for Mass. They facilitate seating at crowded Masses, the taking up of the collection, and the communion procession. Both men and women with the ability to be gracious hosts and to make people feel welcome are called to this ministry.