musicus wrote:I really don't see why a new translation of the same Latin text should imply or require musical stylistic innovation. .
Logically this observation might be true. However, in practice major changes to text usually do result in stylistic shifts, especially if there has been a time gap of a decade or more from the previous one.
The basic reasoning behind this is as follows: New texts encourage composers to write new compositions. In turn this encourages them to take a fresh look at how to treat texts. Also, if there has been a time gap since the last set of textual changes, then new composers might be attempting to write new settings suffused of course with their own stylistic approach. Such attitudes have maximum effect with composers who are interested in 'word painting'.
Against this, though, is the undoubted fact that new texts also encourage musicians to adapt existing repertoire to suit the new situation. Moreover much church music, because it is functional, has a tendency to be anodyne, because people do not want it to intrude too much on the act of worship through a liturgy. In this atmosphere musical 'word painting' can stand at a discount. Music that is anodyne is therefore likely to show less abrupt changes in style, though of course this can happen.
In this context the following points might be noted:
 The introduction of vernacular liturgies in the late 1960s and early 1970s certainly coincided with a vast surge in new compositional output accompanied by the introduction of new styles.
 Note too that this coincided with a change in liturgical philosophy - a shift towards congregational singing away from the 'traditional' SATB-Organ nexus that had hitherto predominated (apart from efforts in the 1930s to promote the congregational singing of plainchant).
 The present textual changes to the Mass also coincide with a shift in liturgical philosophy: i.e. the emphasis on an 'authentic liturgy'. Crudely put this means a literal observance of the text. So the use of paraphrases of the text, metricalised versions of the text and other similar practices (e.g. the Peruvian Gloria) all stand at a discount. There have also been signs that 'Traditionalists' have hoped that the new texts will promote their cause by pushing Catholic musical-liturgical culture back towards a pre-Vatican II state.
In this context note the tension between those who hope to use music to heighten and add to the liturgical experience versus those who see it as providing an accompaniment or backdrop to a text that must not be intruded upon or distorted by musical style. The current stress on 'authentic liturgy' weights the balance in favour of the latter group; so church music is likely to become more anodyne.
 Even without textual change there have already been building up a number of pressures for stylistic alteration. e.g. The attack on the 'Four Hymn Sandwich', the disparagement in certain circles of 'Folk' styles, a new attempt to revive plainchant - including new adapatations to fit an English text (itself a potentially significant stylistic development), the decline in the use of instruments other than the Organ/keyboard. On a broader musical front Classical musical taste has shifted away from 'modernism' towards modern tonal styles (e.g. Karl Jenkins, Arvo Part, John Taverner) and the 'stock' of late Romantic composers (Elgar, Brahms, Schumann) has risen enormously. There has also been something of choral 'counterattack' with outfits like Army Wives choirs etc. Viewed this way textual change is the excuse for alteration, not its cause.
 There is the question of the supply and balance between different sorts of musicians. If this changes then so will the musical style. So, the revival of choral singing and the decline in the supply of competent instrumentalists will to some extent dictate the techniques composers will use as well as determining what items from existing repertoire will be preferred and what will be neglected. In addition the church can (and has in the past) taken steps to adjust the supply of particular sorts of musicians (e.g. the development of the large musical establishment at Leeds Catholic cathedral). The introduction of new texts can therefore act as a 'forcing draught' to speed up the effects of such changes with all the stylistic changes these imply.
So, textual change will very likely produce stylistic alteration, but it can also act simply as the trigger for something that already might happen. In the present climate the trend is likely to be in a 'conservative' direction. We therefore may have the paradox noted earlier: Contemporary music, in the literal sense, will be 'old fashioned' in style. Music written in earlier decades (cf. 1970s, 1980s, 1990s) might seem more 'modern' in style.