Propers, which are scripture and often in the voice of God, are the part of the choir, not the congregation.

Hymns are devotional and are us addressing God (or devotion to Saints).

Other objective reasons to exclude those songs:
1. There are preferred options and defaulting to “alius cantus aptus” (another suitable song) is literally scraping the bottom of the barrel. The church gives instruction on what to sing, and options if, for good reason, the ideal cannot be executed at a certain time. Too often the exception becomes the norm.
2. They are rife with problematic, or at best questionable, theology.
3. They are often not designed for congregational singing. Neither are Gregorian Propers, but if the argument for their use is “these are the songs the people sing,” they probably don’t. Problems with range and rhythm make them difficult for a singing congregation to execute, and many congregations that frequently employ them are not a singing bunch anyway. They just like them as a backdrop to their Sunday obligation.
4. The entire reason for music at Mass is to sing THE Mass, not sing AT Mass. If they provide nothing but a loosely religious text set to a tune, they serve no purpose besides elevator music. Which leads to:
5. Turn the question around. Why SHOULD they be sung at Mass?

3. They are often not designed for congregational singing. Neither are Gregorian Propers, but if the argument for their use is “these are the songs the people sing,” they probably don’t. Problems with range and rhythm make them difficult for a singing congregation to execute, and many congregations that frequently employ them are not a singing bunch anyway. They just like them as a backdrop to their Sunday obligation.

This is actually really not true and is a weak argument. Any congregation that has an emotional attachment to things like Here I Am, Lord usually sings them quite fully. There are lots of other good arguments, but this isn't one. Even things like Be Not Afraid, which have problematic rhythms, people sing quite enthusiastically (even if not following the written rhythm).

Excuse me for starting with the obvious, but it's necessary to make the argument.

Music with words (or words set to music) has two components: the words and the music.

In order for something to be suitable for the public worship of the Church, not only do the words and the music have to be appropriate for the public worship of the Church, but they have to be appropriate for each other.

Sicut Cervus by Palestrina, and Like as the Hart desireth the waterbrooks by Herbert Howells match the text of Psalm 41 as excerpted from the Easter Vigil. They're both strikingly beautiful pieces of music, but one is in Latin and the other is in a Sacral English. If being in Latin is a requirement for the public worship of the Church, the Howells' piece is unsuited to the task, but not because it is, in itself, bad music. If being in the vernacular is a requirement, the Palestrina is unsuited to the task, even though it is beautiful music.

Song of the Exile by Haugen, sets a portion of the same text, but has the disclaimer "paraphrased by Marty Haugen", which means that (whatever else is true) the text of the psalm has been altered to meet whatever needs Mr. Haugen sought to address. As soon as it paraphrased the psalm, it became unsuitable for use as a Responsorial psalm, whatever else it might be suitable to do. The fact that it is written by a non-Catholic isn't what makes it, a priori unsuited to use at Mass. The fact that the composer is a modern writer doesn't make it either suited or unsuited to Mass, at least not necessarily.

If the music is setting a responsorially planned text, then both Howells' and Palestrina's pieces fail, not because they're otherwise bad music or bad texts, but because the particular place in the liturgy which is being filled is a responsorial psalm.

Here I am, Lord goes back and forth from the apparent words of God ("I the Lord of sea and sky") and the words of His presumed servant ("Here I am Lord") without any differentiation, since -- as someone astutely pointed out -- this is intended to be sung by all, throughout. If ye Love me doesn't suffer from this confusion. Dicit Dominus is reported speech, and identifies itself as such. Quotiescumque manducatis, the words of St. Paul, has a melody which exemplifies the warning which he attaches to the text. Caro mea vere est cibus which is the text of the Communion antiphon on the feast of Pope St. Pius X has a melody which accentuates "sanguis meus" and "meam carnem" (appropriately enough). Since it's the feast of the Pope who lowered the age of first Holy Communion, drawing attention to these is quite proper. No where does the text say how wonderful the recipient is, nor is it the recipients blood or flesh which is being discussed.

Using the words of God isn't wicked or inappropriate, by itself. Some style of music are unsuited to the public worship of the Church. Combining the unsuitability of the music as music, with the pronoun confusion renders Here I am, Lord never appropriate for Mass.

I think I understand the concerns of the individual who thinks those songs speak in the voice of God. There has been a definite shift from what I refere to as "God centered " to "you, me and I" centered hymnody. For example, "I need thee gracious Jesus" vs. "I am the bread of life". "O God of loveliness" vs "You satisfy the hungry heart". "O Sacred Heart O love divine" vs "Remember me". This distinction may not seem obvious to some of you but I am not the bread of life, and you can't satisfy the hungry heart. On the other hand , I do need Jesus and our praise should always be to God and His sacred heart and not about me. Of course not everyone will agree with my reasoning but I hope you can see the difference.

Schoenbergian,

Would you consider appropriate a text which quoted " I am the Lord Thy God; thou shalt have no strange gods before ", and which was set to music which was unmistakably narcissistic?