And if we trust that part of the Church’s teaching, why should we not trust the Church’s teaching on how we may receive Him?
Because of the many, many, MANY times the Church condemned it, and reasserted that condemnation, beginning in the 300’s and not wavering until the 1960’s due to widespread disobedience to the universal prohibition against receiving in the hands.
Because when the Protestants wanted to ensure that people didn’t think the Eucharist was more than a symbol, they abolished the act of receiving on the tongue.
Because the permission to receive the Eucharist in the hand was only given to countries who had already established widespread disobedience to the prohibition against it.
Because permission was granted with several restrictions which are not all met and, therefore, to receive the Eucharist in the hand the way we do is, in fact, a violation of the terms of the permission granted. (That is not the fault of the persons who receive in the hand in obedience to their local ordinary. Their lack of culpability does not make it less true.)
Because a maxim cannot be both true and untrue at the same time, and in the same way. It cannot be true that the particles of the Eucharist are so precious that we zealously guard against their loss or desecration in the way we treat the objects that contact them, while at the same time being true that those particles that are lost on people’s hands are no big deal. It is one, or the other. We treat the Eucharist with less care than the vessels that we use to contain it! Jesus is truly present, and so it can only be true that the Eucharist is worth vigilantly protecting at all times, and in all circumstances, to the best of our ability.
Because it is not the Church’s teaching! It is a reluctant exception that was borne from disobedience and the hard hearts of man.