To cut a circuitous argument short:
If you think cabinet minutes shouldn't be released, why not put it into law? Otherwise we end up with the current situation where they're not officially exempt, but will be vetoed every time. If you're in favour of this reform, why not implement it after the other reforms that affect cabinet?
If you think the system doesn't work, why not expose that for everyone to see, before building it back up? If your secret service is going around secretly killing people rather than protecting them, you don't tell people off for revealing these killings on the basis that we should have a secret service to protect people and its activities should be secret.

But perhaps all this is a political distraction. If people see these minutes are they going to think FoI is a cure to bad cabinet government rather than just evidence for reform? Is putting energies into arguing about FoI really a distraction from more serious reform? Or would releasing these minutes be crucial evidence in motivating people to reform the system?

If you think these minutes could be an important motivator for the right kind of reform, you should support their release, if not, you should oppose it. What we really need is for someone to leak them...