In 2012 the Law Commission did another review of the OIA. They noted that the problem had not been fixed over the past 15 years, and reiterated their earlier recommendation. Successive governments again did nothing.
Why the repeated and long-term inaction? Well, from a Minister's point of view it is perhaps convenient if you can "transfer" a request to an agency who does not hold the information being sought and which therefore cannot answer, and it is especially convenient if that decision can never be reviewed and you can never be called on your bullshit. So its just self-interested arse-covering from those at the top.
(I have an example of exactly this sort of shitfuckery from Chris Hipkins, who transferred a request for advice about his chosen extension date for the COVID-19 Public Health Response Act 2020 - a date which seems to be a clear violation of Parliamentary intent - to the Ministry of Health, who turned around and said "the Ministry of Health... has limited involvement in this as the decision on timing sits with Hon Chris Hipkins". Sadly, they were too chickenshit to send it straight back to him, despite the requirements of s14(b)(ii)).
As for what we can do about it: Graeme Edgeler has drafted a bill to fix the complaint provisions, allowing transfer decisions (and various other decisions recommended by the Law Commission) to be reviewed by the Ombudsman. You can read it here. It would be nice if some MP picked it up and put it in the ballot, and like the bill extending the OIA to cover parliamentary undersecretaries, would seem to be a slam-dunk for actually getting passed.