I think we are the only ones who get caught up in what instruments God might like or accept as worship, which begs the question “Who do we think we are?”. I have had people tell me that we shouldn’t play that music because God would find it offensive, and I’m like “Your kidding, right?”. Here are some lyrics from a contempory praise and worship song, tell me if it doesn’t talk to the soul,
It talks to the soul! Those are some good lyrics
Is the music as good? What is the title, and artist? No doubt, its what is in our hearts that matters most to God. Although, at the same time, someone’s music can affect what’s in others’ hearts too; so its not like a blank check to do whatever pleases us. But I like listening to the Christian Contemporary music channel. It has great singers, great melodies and harmonies, and a nice variety of good music, all with moral and uplifting lyrics - which is more than we can say for the rest of the new music out there. 
And ‘Pange Lingua’ (“Sing my tongue the Saviour’s Glory”) was to the tune of a marching song sung in the Roman army.
The document also notes the following regarding instruments:
Thus, there are parameters, unfortunately, they are often ignored by those who. while sincerely believe that this genre is acceptable, perhaps have not noted that Pope Paul VI wisely observed that not everything is fit to enter the threshold and, as Pope Benedict XVI, himself, said in Sacramentum Caritatis, certainly as far as the liturgy is concerned, "we cannot say that one song is as good as another.
Just a slight clarification… it wasn’t actually the melody, but more of the rhythm and the stress-accents, with alternating triple meter that were used which resembled the marching song, since it was originally intended to be used for procession. It basically resembled the use of meter in rhymed, classical/Latin poetry, which was also used in a developed new style of hymnody during Acquinas’ time. Today the rhythm and stress-accents are not usually employed and sung in a more plainchant style.
Ultimately, however, the practical application of these norms is done by the bishop, who is the chief liturgist of the diocese. I have yet to find a bishop who has publicly disallowed the use of guitars or Praise and Worship music in liturgy. Neither the Magisterium nor the USCCB has made any specific statements about guitars or praise and worship music specifically AFAIK.
And once again, I will state that these statements are very vague. Forgive me for continuing to hammer this home, but I really don’t care to step down on this issue.
The “vagueness” has been a major critique by most people who are concerned about the music liturgy since Vat II and even with the subsequent docs that came out afterwards. It is one of the things which still perpetuate this particular, ongoing controversy. Because of the vagueness it has created a more liberal interpretation of what can be used. Although the Musicam Sacram does specify that the newer music must “grow organically” from previous forms which make more sense in terms of people who are musicians, especially when you look at how sacred music in the past had to be refined to reflect more of what was accepted previously. But for those who aren’t really musicians or who aren’t musicians at all, that term can mean a variety of things and leaves it open.
Again another one of those things in the documents which have people who truly want to do the right thing for the Church pulling their hair out. It was always, “It should be done this way, however…” thus leading to the ambiguity. For me, it should be common opinion of real musicians who are leading experts both in the field of music AND of liturgy, and also of the Pope since he is the head of the Church and in the past popes have banned certain styles of music as well as other specifics in music (tri-tone for example) until the music could be refined, etc. That said, the ambiguity of the documents do not specify, thus the vagueness again.
Sometimes, sadly, that is the case. It’s either that or lose your job. At the moment, I see that there seems to be more of a crackdown, though, which has been needed. And there is the natural human reaction of trying to resist it. That said, the priest does have to submit and listen to his bishop or the authorities he has put in charge within his diocese. For instance, like in our diocese the bishop has been trying to work hard at this, with having our director of worship in charge who is very well-versed and knowledgable of what should be used at mass especially since he has come from Rome. But they are still getting resistance, much of it from parishes in the suburbs. When you are given a bit more freedom, it’s hard to give it back once the higher ups realized it went a bit too far and try to reign it in. So, if one is a music director or even a parishioner at a parish and knows what the bishop and his director of worship requires for the Mass, it is the responsibility for one to at least make it known to the pastor (who may or may not already be aware of it.) At that point it is up to the pastor to do what he wills of the information, by doing more research, etc. and then if the changes don’t occur and after speaking with them again, then perhaps it should be reported to the DofW.
And, my response is based on the Instrumentum Laboris, the document that the Fathers of the 2005 Synod on the Eucharist used:
And these comments came from bishops, mind you.