I am all of a dither on this one.
Ignorance is definitely NOT bliss and denial is self destructive.
But if we are monitoring closely at home, then personally I take my bg readings as a far better indication of how things are going than the HbA1c which seem to bear little relation to my home readings across time!
By opting in, the surgery gets a bit of income, and spends it on me, which I don't need because I am self monitoring.
By opting out, the NHS still keeps the money, and presumably it will get spent somewhere, hopefully more usefully, if I am already monitoring my own situation well at home.
People who don't turn up, or who don't respond to the letter, are very unlikely to be self monitoring, but at least the surgery has shown willing, and can prove that deterioration in the patient's condition isn't due to negligence by the surgery.
If T2 is (as the NHS believes) an ongoing deteriorating condition leading inevitably to complications, then regular checks are VITAL, even if they may only slow the downward spiral.
If T2 is (as I believe) hugely controllable, with care, diet, monitoring and NHS assistance (when needed), then those regular checks may not be nearly as necessary.
Can't really see a clear path.