I don’t think white, American, middle- and upper-class are the best categories in this case. Instead, I’d suggest something like the degree to which someone is steeped in or identifies with Mormon culture as it existed before, say 1970 (which was predominantly white and American). So a lifelong church attender raised in Arizona stands a good chance of having picked up a Mormon manner of prayer, I would guess, while a recent convert would have to make a conscious choice to adopt it, or not. Think of it as the verbal equivalent of wearing a white shirt to church. (I disagree with the class restriction, however; I’d guess that the linguistic features of Mormon prayers are equally or more prevalent among rural congregations, for example.)

One thing that is probably included in your point above about public prayers being a “lived tradition,” but which might deserve a little more emphasis, is that public prayers on one potentially rather important way in which we place ourselves in the midst of our family lineage and heritage. There are phrases that I use in my prayers–such as “bless us with our needs and our righteous desires”–that probably have long been used by millions of Saints, but which I learned most specifically from my maternal grandfather, and whose face and tone of voice I can still call up in my memory when I say those words. I’ve become, through my speech, a carrier of his legacy of faith.

I also found your comment about the white upper- and middle-class English-speaking American Mormon (because, of course, that is what this post is basically talking about) tendency to choose some variation of “father” over “God.” The same thing would go for the lack of references to “Jesus” in our prayers, as opposed to the more formal “Jesus Christ” or, even more commonly I think, the third person “the Savior” or “the Redeemer.” As I’ve said before in other contexts, our collective distaste for things smacking of most kinds of evangelical Protestantism goes overboard, sometimes.

Do note that these arguments may be a bit tendentious. My point is that what we mean by ‘poetry’ or verbal art outside of the modern traditions we’re familiar with is broad enough, and the features of Mormon prayer are unusual enough, that an outside observer might decide that the characteristic Mormon art form are our public prayers.

“Dear HF
We thank thee for this day.
We thank thee for the gift of thy Son.
We thank thee for this opportunity to come and renew our covenants.
We thank thee for the freedom to worship in this blessed land of ours.
We thank thee for the leaders of the church.
We ask thee to continue to inspire them with the inspiration they need.
We ask for thy Spirit to be with us here in this meeting and to be with us the rest of this day.
In the name of . . . Amen.”

This type of Mormon public prayer is a convention. And hence, its repetition is, at best, a performance. Show me what I’m missing, because heaven knows that I’d like to witness a little art in Sacrament Meeting, instead of the usual pharasaic/Zoramite repetition of phrases. Please.