Yep, all for improved security.... From Internal affairs website:

As of 4 November 2005 the fees for New Zealand passports and travel documents have changed.


and

The Passports Amendment Act 2005 came into effect on 21 April 2005. As a result of this legislation there have been some important changes to the New Zealand passport:

* All newly issued passports will have a maximum validity of five years
* We can no longer print name endorsements in a passport.

...the dodging...

Why was there no notice of the new fee? Isn't this a breach of usual practice?
The Department of Internal Affairs did not provide advance notice of the fees review because analysis indicated that this would create unmanageable demand for passports. This would have seriously compromised our ability to deliver passports for those people who had already arranged, booked and paid for their travel.

While we usually give some notice of fee changes, there is provision for new fees to come into force the day after their notification in the Gazette, which in this case was 3 November 2005.

and from the NZ Embassy in Bangkok website (but not found on DIA website):

From July 1 extra visa pages will NO LONGER be inserted.
The Department of Internal Affairs is introducing biometric passport technology in the second half of 2005, and extra visa pages are NOT compatible with the book construction.


There you go...!