I don't know if it is my imagination, but since Pentax returned my camera's K10D's and since my firmware update, it seems that my exposures are better. They don't seem as underexposed...

Yes. The new firmware tweaks some settings. It doesn't, however, solve the issue with the green button and M or K lenses.

As a studio photographer, I don't find this to be much of a problem. I doubt that you own any of the old classic glass. But there are lots of photographers who have valuable collections of amazing Takumar and old M and K glass that would like this solved.

For now, I just use the ol' Sekonic meter and don't worry too much about the camera.