We are not supposed to go to Mass with an empty "basket" waiting for God to "fill" it. (We are especially not supposed to go thinking that the priest, the choir, our friends, or other human beings will "fill" it.)
We are supposed to go to Mass with a "basket" full of the stuff of our lives--good and bad. We are to come with our "basket" and offer it up to the Lord at the altar.
We may wonder why we can't just do this at home. That's a good question.
We need to go to Mass to give the Lord all our joys and pains, because, at Mass, Jesus makes present at the altar, across time and space, His Sacrifice on the cross in an unbloody manner. This is what the Catholic Church teaches. The Mass does NOT sacrifice Christ over again. It happened once and for all (Hebrews 10). God, in His power, has made possible, in every Mass, for us to be present at the foot of the Cross. How is this possible? With men, this is impossible; but with God, all things are possible (Matthew 19:26) because God Himself is above and beyond time.
We are to go to Mass, not to be entertained, or to watch passively, but to join with Christ in offering our sufferings and joys to the Father, and receiving His Grace in return. Because God is all good and all powerful, these graces are imparted to us whether we feel it at the time, or not. Thank God He does not rely on our fallible and changing emotions in order to care for us!
Mass is important and powerful because each Mass brings our salvation history to us. We begin with the confetitor (the "I confess"). We turn to Christ in all humility and acknowledge our sins and ask Him for forgiveness. We confess with our lips that Christ is our savior and that we, as human beings, cannot live a sin free existence without the help of the Lord. We, as fallible human beings need to confess our sins to God and each other often--every day, even. The Mass helps us to turn our hearts and minds to God because God is present to us in Mass, in a way that He is not outside of it.
Jesus appointed the disciples, who in turn, appointed others in an unbroken line throughout history, to stand in His place (in persona Christi), teach us the faith that was taught to them by Christ, absolve repentant sinners, and make present His saving Body and Blood to us .
Our Lord's words "This is my body, which is given for you" (Luke 22:19) correspond to those of Exodus 12:27: "[This ritual] is the sacrifice of the Passover in honor of Yahweh" when he freed Israel from slavery in Egypt.
The words "For this is my blood of the covenant, which is poured out for many for the forgiveness of sins" (Matthew 26:28) echo those of Exodus 24:8 when Moses says: "This ... is the blood of the covenant that Yahweh has made with you."
(The Mass makes) present Christ's unique sacrifice on Calvary and in doing so ratifie(s) and renew(s) the new and eternal covenant.
Therefore, God has commanded us to worship with a sacrifice, his own unique sacrifice.
~quote from EWTN
If Jesus had not wanted us to come into His Presence at Mass, He would not have told His disciples "Do this in memory of Me." (Luke 22:19)