I suggest a reason that it is so ubiquitous is that we need to hear its message, one of the love and protection that God offers to all of us. A love that protects, comforts, and just is always to be counted on.
John H. Hayes, in Preaching through the Christian Year B, points out that two different images of God are used in this psalm--shepherd and host.
First, the psalm begins, "The Lord is my shepherd." When we are in danger, or in need of direction, we can be comforted with that image of a shepherd taking care of the sheep who really need being taken care of, including being protected from predators, and being told when we are on the wrong path and being shown the right way to go.
Also, the psalm includes, "You prepare a table for me....." The Lord welcomes us, is generous with us, and will continue to do so; "I shall dwell in the house of the Lord my whole life long."
Hayes summarizes the diverse expressions of human experience found in this psalm:
One set emphasizes the troubles that threaten to overwhelm human life.... Another set stresses the positive instruments and acts of God's care.... Human life, of course, experiences both the negative and the positive.... This psalm presents the human predicament without any illusion about persons/ being superhumans and above pain, loneliness, and lostness; yet the symbol of God as protector and even corrector affirms the potential of a tranquil life lived amid adversaries and the harsh realities that are the ingredients of every life.