For some reason this always rubbed me the wrong way. On one hand, I am worthy to receive God's grace and the eucharist meal for that matter. God made me worthy when God made me in the Divine image. And if that's not enough, Jesus made me worthy by the sacrifice he made on my behalf.
On the other hand, perhaps I am not worthy without Divine help and intervention. And this prayer is a reminder of that gift of grace that God alone can dispense. As a priest, I do not feel worthy to offer absolution, but instead give the assurance that no matter where you are, or how far you have moved away from God, you are never beyond the boundaries of God's love.