Quia semper pecco, semper debeo accipere medicinam (Ambrose, De Sacramentis, 5.4 cited by AC 24).
A neglect of the eucharistic sacrifice Is perhaps also to blame for the infrequent use of the Lord's Supper in generations past. For a pietistic fear of unworthy participation is itself a departure from the eucharistic sacrifice. To fear that we are unworthy of the Lord's Supper Is to evaluate ourselves on the basis of our won works and merits, and to view our sin as greater than the crucified body and shed Blood of Christ…That Christian is truly worthy and well-prepared who believes these words, "given and shed for you, for the forgiveness of sins." Such belief is the eucharistic sacrifice. It is the very opposite of fear (Stuckwisch, Philip Melanchthon and the Lutheran Confession of Eucharistic Sacrifice, 3-4).
Luther on While we are in this tabernacle, we longingly sigh and are depressed. 2 Corinthians 5:4.
“If you say you feel no sin, death, world and devil and have no battle and strife going on against them and why this struggle forces you to go to the Sacrament (I.e. to the Holy Supper), to that I say this: I hope you are not serious, that you alone among all the saints and people on earth are the one person who does not feel these things. And if I knew that you are serious about this, then I would want to order that, on all the streets where you would be going, all the bells would have to ring out and shout out before you: “Here enters in a new saint above all the rest of the saints who feels and has no sins!”
However I would without joking tell you: “If you actually no longer feel any sin, then you most certainly are dead in sin, and this is already such an over the top huge sin; namely, that you really think you have no need or desire for the Sacrament. You then have no regard for God’s Word and have forgotten about Christ’s suffering. You are stuck and filled with ingratitude and suffering from all sorts of spiritual problems.”
Eckardt, "Why the Sacrament? Why Not the Word Alone?," Gottesdienst, 21:2: conclusion is that to say that a non-communion (prayer = preparation for mass) service is just as important as the Mass is, in effect, to say that the Incarnation of God is of little significance!
Eckart in Gottesd. 2020:4 gives a fair and charitable summary of our fathers' infrequent communion practice and why he would prefer that to a sub-Lutheran (CoWo) church that had frequent communion.