How do you know besides your opinion that the centerfold problem is a manufacturing problem instead of a limitation of current technology?
Even my Aptus17 suffers from centerfold when I put it in the right circumstances, actually I can even push it so it shows 6 rectangulars 3 by 3 with a centerline. I think a lot of sensors (if not all) suffer from this provided they are pushed in places where you should not (when you do not wish to pay the penalty).
The other stuff you mention being limitations of technology are also varying in degrees of severity considering sample variations. When these are only limitations due to the technology why would there be any sample variation?
All in all, whether they are manufacturing errors, variations or technological limitations, the problems are there and need to be addressed.
Somehow it seems like it is worse when it is a manufacturing fault instead of a technology barrier, why? So you can point an accussing finger towards the manufacturer? Pfff.. I don't really care what the reason might be, I am not into blame only in solutions.
Actually I would prefer a manufacturers fault since that can be resolved much more easily than a tech barrier.
Indeed the centerfold is a lot easier to address with the custom gain adjuster than any form of CA or purple fringing (not taking distortions in consideration, DxO is fairly good in fixing these).