More about the "in, with, and under" question

A thoughtful reader suggests that "in, with, and under" is a good way of describing Luther's biblical doctrine of the Supper, that it especially deals well with the erring Roman doctrine of transubstantiation, which teaches (stemming from St. Thomas, and back further to Aristotle's theory of substance and accidents) that we eat only the Body and Blood: that the appearance of bread and wine become -- after the words of institution -- merely "accidents" of the reality there.

(To me, the most persuasive argument against Rome is I Cor. 10.16: "The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?" In other words, St. Paul states plainly that the cup (meaning the wine) is a "communion" (Greek: koininia) of the blood of Christ, and the bread is likewise a communion of the body of Christ. So we have both wine and blood, both bread and body).

"In, with, and under" may be a good explanation of Luther's doctrine. I'm still not persuaded that our current usage is necessarily bad. But a couple of things come to mind.

The first is to ask why -- if a good explanation -- did Luther himself not describe it that way? Obviously, he used all three terms in the text of the Small Catechism; why not all 3 together here in the explanation of the Supper?

The other is to question if Luther's explanation was solely directed against Rome's errors. Hermann Sasse used the phrase "the lonely path" to describe the fine line that Luther had to walk between Rome's error on one hand and Protestant errors on the other. Zwingli (and less directly, Calvin) argued strongly against Luther's teaching on the Supper. In writing the Catechism, Luther no doubt had these errors in mind as well.