That's from the 2003 rubrics.
Guess what a lot of "ministers of music" inflict on congregations?
Yeah, that's right. Banal songs and gross (nearly unrecognizable) paraphrases of the Psalm.
The real scandal, here, is that their Pastors let them get away with it.
What about the psalms that ARE put to music?
Because of
1.) Ignorance
2.) Belligerence
3.) Laziness
4.) A combination of #1 and #2