Right, I understand. But isn’t it still fundamentally accurate to say that we have a full-scale Mass, as on a Sunday, where the liturgy follows the GIRM’s prescription, and then we have a daily Mass where various parts of the liturgy or its adornments are omitted? And isn’t that so regardless of the many internal gradations that could be found in either—whether or not incense is used, whether various parts (Sanctus, Our Father, etc.) are sung or spoken, and so on?
And to the extent that that is so, isn’t it helpful to have a vocabulary that can express that basic structural difference?
And if it is, since “weekday” vs. “weekend” just won’t cut it, isn’t the high Mass / low Mass terminology well-adapted to that office?
It is not. It never has been, since as accurately pointed out by a poster, even in the older rite, a Sunday Mass could be Low Mass. In the older rite, the High Mass was clearly distinguished from a Low Mass:
Solemn High Mass: all parts sung, incense used, six candles on the altar, deacon and subdeacon used, choir used.
Low Mass: no parts sung, no incense, two candles on the altar, no incense, no deacon and subdeacon.
Midway between these two is the Sung Mass, commonly called High Mass: same as the Solemn High Mass but without the deacon and subdeacon. Incense is used by permission, now generally given.
If the parish had no choir, then the priest would have no choice but to celebrate a Low Mass on Sunday.
In the modern rite, this strictness was dropped, and Masses could be “mix-and-match” so to speak. Since we now use the principle of progressive solemnity, it’s not accurate to say “High Mass” and “Low Mass”. More appropriate might be the terms “solemn Mass”, “sung Mass” and “spoken Mass”, but these will by no means be de jure terms as were the older “High Mass” and “Low Mass” monickers.