Maybe its a school by school thing? The girls' school is Christian, rather than Catholic so maybe that's it? I must admit, I don't understand the changes. While sometimes things need to be modernised, I don't think the language used at my girls' school improves it, simplifies it for the kids or brings any benefits. It just confuses us old people who still remember the Lord's Prayer from their own days at primary school ;-)
Ah yes it may be a Christian change. Catholicism is very traditional when it comes to the set prayers and rituals