In browsing through the Pewsitter page, I came across this excellent article by Fr Christopher Smith on the Chant Cafe blog regarding "Praise and Worship Music". I suggest its close study, as I think he is spot-on. A little personal background is in order. Several decades ago, when I was young and naive, I not only attended "guitar Masses"; I did them. Week after week, I hauled my 12-string to Mass and performed with several others. Granted, at that time I was a victim of youthful ignorance and lousy catechesis.
About 20 years ago, when I started doing my own research on my Catholic heritage, I realized that such music is not appropriate for Mass for all the reasons Father Smith succinctly states. (No more would I pick up a guitar at Mass.) I think that it is also part and parcel of the progressive movement to divert attention from The Unbloody Sacrifice of the Mass and to excite the emotions. In saying that, I speak as a musician who was trained on methods to elicit emotional responses from the congregation. Notice Father's 8th point about conversion being primarily an act of intellect and will. The role of emotions is secondary at most. However, such confusion about emotions is only symptomatic of our culture, which does place feelings over thought - often with deadly results. Also look closely at point #9.
There are a few other points that I do think Father overlooks. If you've been in older churches, you'll notice that they all have choir lofts in the upper rear of the church. I think the reason is very obvious. Attention was never to be focused on the choir, and this location was deliberately selected to prevent that (I'm sure it was elevated to aid in acoustical considerations). Now they're often in front; where do you see a lot of people look during the singing?
Fr. Smith touches upon the aberrant liturgies of the Life Teen organization. He mentions that none of his Life Teen friends are still practicing Catholics. I for one am not surprised, as the apple generally doesn't fall too far from the tree. What can that possibly mean? Consider that one of the three founders of Life Teen, Fr Dale Fushek, was excommunicated by Bishop Olmsted of Phoenix several years ago. Read this article and notice the comment by Stan and Jan Nicpon. Such are the fruits of misplaced emphasis on emotions.
It does appear that people are finally waking up. They are forsaking the music of overgrown hippies and discovering their true spiritual and cultural heritage, and not a moment too soon.