I recently posted this as a comment on The New Liturgical Movement blog, and I’ll post it here. It refers not to P&W specifically, but to any pop-sounding music.
I think the whole question of the associations which pop-sounding liturgical music triggers in the mind of the listener needs to be discussed more, since it is just those associations which are usually given as a (the?) reason for using such music in liturgy. That is, that style of music is used precisely because it sounds like the music heard “out there”, in the secular world.
The problem that I see with inviting those associations is that “out there” just does “out there” better, more naturally. “Out there”, the secular world, is implicitly or even explicitly taken as the model, and the resulting pop liturgical music attempts to adhere to that model while using more appropriate words.
The usual result is that pop liturgical music, when judged by the very standards it has itself invited, comes across as a day late and a dollar short. It’s just not as good as “the real thing”. This is both because those secular musicians doing “the real thing” are better, or at least have better recording and engineering staff and bigger budgets, and also because music that attempts to imitate pop culture is going to be much more self-conscious than the secular music that just bubbles up from the pop culture.
But whether done well or done badly, the associations remain, and the associations make the liturgy, and by implication the Church, out to be followers, copycats, secular wannabes. Rather than the liturgy existing in isolation as what it is, it can end up coming across as a rather sad and pathetic pop-culture groupie.
Pop culture music as model, or Gregorian chant as model (“On Sacred Music”, John Paul II). The two models are worlds apart, and the resulting compositions and associations naturally end up worlds apart as well.
I would also point out that the ideal for liturgical music is that the music is to be in service of the text. That is, the text is primary. Thus we see that chant and polyphony is by and large unmetrical. It doesn’t have a fixed beat and a constantly repeating structure, because the music is built around the text. With a strong fixed beat and repeating structure, on the other hand, the words must be built around the music. Thus the words must be trimmed, pared, stretched, twisted to fit onto the skeleton of the music. This goes against the ideal for liturgical music, making the text secondary to the music.