Originally posted by paperbag846 I honestly believe that sharpness is the most overrated aspect of lenses
I find this to be largely true as well. Once a sufficient level of sharpness is reached (and most of the current Pentax lenses reach this level, at least across most of the frame and at most of their focal lengths), additional sharpness is not going to have a great effect on how most images turn out. It's the microcontrast, the color rendition, the overall beauty of the rendering that will make the biggest impact.
One can find plenty examples of lenses with less resolution producing better images than lenses with more. At least in terms of center resolution, the 18-55 is sharper than the DA 10-17, but the 10-17 will tend to produce better images, because it has more contrast and better color rendition. I've seen resolution tests where the old M 50/2 actually outresolved (by a small amount) the M 50/1.7. But the 50/1.7 is clearly the better lenses. The M 50/2, despite its commendable sharpness, produces (relative to the 50/1.7) flat colors and uninspiring contrast.
Lens that have excellent microcontrast and produce rich or striking color often seem sharper, because they produce images with more "snap" or "pop." So I suspect that some people confuse measurable resolution with contrast and color rendition. To judge a lens, one has to look at the images it produces, rather than how well it resolves MTF charts. (How many people buy a lens to shoo MTF charts?) It's the quality the images a lens produces, not how well it scores on numerical tests, that is important.