No, this post is not designed to fire up the "style wars," for there really shouldn't be any war, and, as my friend Jeffrey Ostrowski points out, there is so much confusion about what actually constitutes a style to begin with, these discussions hardly go anywhere.
What's important is the issue of authority on the style question. The USCCB document Sing to the Lord contains a claim that "in recent times, the Church has consistently recognized and freely welcomed the use of various styles of music as an aid to liturgical worship," and cites Sacrosanctum Concilium 123 as decisive support.
At the MusicaSacra forum, Aristotle Esguerra astutely observes that there is a serious citation problem here. Section 123 in SC does NOT deal with music. Hence the addition of the phrase "styles of music" in STTL finds no justification in the documents of Vatican II. The section cited here is clearly dealing with painting, furnishings, and architecture. As regards music in particular, you have to go to section 116: "The Church acknowledges Gregorian chant as specially suited to the Roman liturgy: therefore, other things being equal, it should be given pride of place (principem locum) in liturgical services."
Why is the principle different as regards furnishings as versus music? The music is part of the structure of the Mass, not an adornment or part of the surroundings. The Church no more admits any style of music than it admits any style of the Canon of the Mass or the Propers or the Penitential Rite. It simply cannot be done. It is very surprising that STTL would make such a claim, and then attempt to justify it with a misplaced and faulty citation.