This question came via e-mail. I am against pressed for time, so I will let you all take care of it.
Good question, though!
Please help, if you deem this question worthy of a broader audience.
The priest who celebrates the extraordinary form for us has a beautiful singing voice and knows by heart much of the plainchant. He is newly come to the Tridentine rite and wonders why it should be the case that the priest intones the Gloria but does not continue to stand at the altar to sing the remainder of the prayer. He has the same question in regard to the Credo. For the Kyrie, Sanctus, and Agnus Dei, he knows that this is not practicable because of the many prayers the priest is offering at the same time.
My question to you: Has there ever been provision or permission for the priest to sing the Gloria and the Creed from the altar, with the choir, rather than taking a seat on the side and waiting out the choir? And if there has been no provision, is there a particularly convincing theological or rubrical reason why he should not do so?
I am reminded of a story told by the late Msgr. Richard Schuler. He knew an old German priest at a rural parish who liked to get the higher stipends for High Masses. Problem: no choir. No problem! He would do all the parts himself!
He would from time to time let the people know, "Und now I am ze chvior", and then would sing for a while. Then, "Und now I am ze priest." And so forth. Funny and really not to be done.
In the words of the immortal Gracie Allen, "People are funnier than anyone."