The additional cost probably has to do with the extra security features the new passports have like micro print, an electronic chip, watermarks, embeded wires...etc. All these anti forgery features add cost and are just passed on to us users. I wouldn't be suprised if the new suped up driver licences they are proposing are going to cost a lot more also.
I got my new passport about a year ago and compared to the one it replaced, it is now nearly impossible to forge. The most obvious security feature is an embedded security chip. The pages are now colored and your mug shot is now printed on the page and no longer laminated.