Whereas it is ordained in this Office for the Administration of the Lord's Supper, that the Communicants should receive the same kneeling; (which order is well meant, for a signification of our humble and grateful acknowledgment of the benefits of Christ therein given to all worthy Receivers, and for the avoiding of such profanation and disorder in the holy Communion, as might otherwise ensue;) yet, lest the same kneeling should by any persons, either out of ignorance and infirmity, or out of malice and obstinacy, be misconstrued and depraved: It is hereby declared, That thereby no adoration is intended, or ought to be done, either unto the Sacramental Bread or Wine there bodily received, or unto any Corporal Presence of Christ's natural Flesh and Blood. For the Sacramental Bread and Wine remain still in their very natural substances, and therefore may not be adored; (for that were Idolatry, to be abhorred of all faithful Christians;) and the natural Body and Blood of our Saviour Christ are in Heaven, and not here; it being against the truth of Christ's natural Body to be at one time in more places than one.
The men who insisted on this explanation knew that ceremonies teach and speak for themselves. They thought they could undo the body language with verbal language - but that's a lost cause. A child who can't follow the arguments of the Real Absence or even understand the Verba can see with his eyes that Something Is Going On Here.
This is why kneeling before the Sacrament is a useful, helpful, and praiseworthy ceremony for Lutherans to recover in our day. It confesses that the Sacrament is the real, true, natural, glorified, risen Body and Blood of Christ - and it confesses it in a powerful, public, and unmistakable manner. The communicants kneeling to receive the Supper certainly confesses this - and the Celebrant should kneel, too, as soon as possible. This is the logic behind not waiting for the reception to kneel, but rather kneeling after each of our Lord's Words of Consecration. What Jesus says goes - when He has said it is his Body, it is. So that's the time to kneel. No need to wait for the receiving.
This confession of the reality-making power of our Lord's Word is especially needed in our midst as a confession against the faith-damaging doctrine of Receptionism.
And this is also why kneeling after each Consecration is sometimes opposed in American Lutheran congregations. Those who have been taught Receptionism recognize this kneeling as a denial of their doctrine - which it certainly is. This provides an excellent excuse for catechesis that is often sorely needed in Lutheran congregations.
And so here again is how a ceremony teaches and actually becomes much more than an adiaphoron. Since the ceremony makes a confession, it cannot be meaningless or neutral. And it cannot be neutered by explaining away a la The Black Rubric. To kneel before the Sacrament is to confess that This is the Body and Blood of Christ not only with the lips, but with the whole person.