Why the sudden change? Catholic churches rarely used the name anyway, even though it appears in several of their Bible versions including the Jerusalem Bible, the New Jerusalem Bible and the Christian Community Bible, all of which contain the Name spelt as Yahweh . They have also sponsored a Catholic edition of the Living Bible, which includes the name Jehovah in the OT over 300 times. The Westminister Catholic version, which was orginally published in the UK , includes the name Jehovah in the OT each time YHWH appears in the original text. The Older Catholic Spanish Versions, such as the Spanish Catholic Bible by Torres Amat, including the name spelt as Jehova a few times in the OT text. Yet many Catholic were encouraged to read the New American Catholic Bible or another Catholic version which did not contain the name. Now it appears they want to take the name out all together.
The argument they use is weak, and in apppears to contradict Jesus himself. They argue that the LXX NEVER used God's name. However, it is now known that earlier editions of the LXX did contain the Tetragrammatton. A more recent discovery of the fragments called "Nahal Hever Minor Prophets" dated around 50 CE, contains the books of Habakkuk, Nahum, Micah, Zechariah, etc. and it includes contain the Tetragram. Another dated LXX fragment dated around the 1st century which contains the book of Job 42, and it also contains the Tetragram. Evidence indicates that the earlier or original LXX contained the Name. Those earlier editions of the LXX were written around the time of Jesus' ministry. However, the Catholic church appears to appeal to the LXX that were written in the 2nd and 3rd, which were available after Jesus' life on earth. Some scholars believe that prior to the mid-2nd century no copies of the LXX contained substitutes for the Divine Name. Instead, they used some version of the Name. So when when Jesus read from the scroll of Isaiah as recorded in Luke chapter 4, he must of pronounced God's name. Jesus did not follow the Jewish custom of not pronouncing God's name. In Matthew 15, he said that the Pharisees made God's word invalid by their traditions and non-bibilcal rules. Jesus instead taught us that we should sanctify or keep God's name holy, and made his name known. (Mat. 6:9, 10, John 17:6, 26). The very name Jesus means "Jehovah's means of salvation", something which the early Christians, who were mainly composed of Jewish converts, must have known. They knew that Jesus was sent by Jehovah to save humankind (compare Matt. 1:21, John 3:16, 36). The apostle Paul while emphasizing Jesus name, as the name GIVEN by which we must be saved, also stated that God had selected the Christian congregation as a "people for his name", and then cited the Hebrew Scriptures which mentioned God's name twice, most likely quoting from an early LXX which included the Name. The 144,000 Christians of Rev. 14 have the name of Jesus and his Father's name "written on their forehead". In Rev. 19:1-6, all of the Christians are said to be worshipping and saying Hallelujah, Praise Jah, Jehovah. So the NT text clearly shows that true Christians will be praisers of Jehovah, making God's name known and sanctifying it like Jesus did.