Everywhere you look in the great mass of content on the subject of photography, you find references to sharpness. Which lens is sharpest? How can I test the sharpness of my lens? Does one sensor produce sharper images than another? How can I make the sharpest possible prints? How sharp do my prints need to be? How can I align my camera to optimize its sharpness?
Even I get into the game, peeking dumbly at the pixels in my digital files, and moaning about the lack of sharpness, and getting out this lens or that to see if it's sharper.
I am sick to death of it.
We see arguments which boil down to: you can remove sharpness later in the process, but you can't put it back in. This is true, but for some reason we rarely see people arguing that you can add chromatic aberration later, or you can remove color fidelity later, or you can remove your ideas later.
Sharpness is but one facet of the technical minutiae of photography. I speculate that the reason we've latched on to it, collectively, is that it's easy to understand, and it's something we can always improve. We can get a tripod. We can get a better lens, or a bigger sensor, or or or. We can spend money to get more of it, pretty easily.
If only it was remotely related to making good photographs, wouldn't that be a wonderful thing?