I'm in two minds really, some data is useful, particularly if a child is in care, that is good to know, children who have had such an unfair start in life do need the balance redressed to some extent in school
Ethnic origins/nationality/language etc, how can you monitor for racism and prejudice without these stats? And if you don't monitor, how can you identify, and if you don't identify, how do you address?
On the other hand, the more data that is provided, the more hours and days staff have to spend analysing it, much of the statistical analysis applied is useless, meaningless and misapplied after woods, eg for berating schools or teachers, ranking, etc
And everyone is going to have a different judgement about what data is appropriate for a school to have, and what isn't.
I would support anyone refusing to supply data, in principle, but in practice, what if you lose your school place?