I have to wonder that the "whole" purpose of establishment of the BaroVNAV approaches is to meet an ICAO recommendation/requirement to have approaches with vertical guidance at each end of the the runway. I'm pretty sure this is what is happening in New Zealand.
It's a relatively cheap/easy way to achieve the requirement without there being the need for any other infrastructure.
The fact such approaches cannot be used by many users doesn't come into it, so long as the approach is there the requirements have been met.