Another horrible fact that proves what you have said. In S and P, no matter what aperture the meter selects, the lens gets stopped down to f/22! At least I can use it in A and M.
I have kept the AF-G 28-80 just because of that. It is surprising good for its poor construction and price. The only drawback with it is that I have it in silver/chrome and it does not look good on my black cameras.