Originally posted by ozlizard IMHO the lens couldnt match the resolution of the sensor.
So far, I haven't found a lens that looked great on my K10D but was bad on my K-7 due to those extra 4+MP. I have lenses that don't deliver in the resolution department, but they don't do that on either camera - they didn't get "outresolved" as a result of a camera upgrade.
Higher resolution sensors, however, require better camera handling. A shaky hand may not get noticed on 6MP, but it will on 15MP. But this scenario is about the camera outresolving the user, not the lens.