I read this article in the New Zealand Herald with considerable interest. There are two viewpoints to take; one, the students; and two, the administrators. Both have, from their own perspectives, valid points of view.
In regards to the students, it's easy to see their concerns. They are having a week of their holidays taken away from them. I am sure that this would be something that students from around the world wouldn't like.
In regards to the administrators, their point is even more valid in terms of teaching and learning. This article from the Globe highlights the impact of overly long summer breaks on student learning and achievement, as you can read in the following paragraph:
'A shorter summer break – of six weeks instead of nine – would be easier to plan for, and also help alleviate the effect of vacation on students’ learning. Many students forget math facts and spelling over the summer, and children from poor families also lose reading skills. An Ontario study found that children from low-income families who had only one month off in the summer did better in math and needed less time for review'.
Perhaps a compromise could be to have the same total number of holidays, but readjust the year calendar to remove those breaks that are too long in duration. This way no one loses; the students get their holidays, while not being away from school for so long that content is forgotten.