The article makes the bulk of the case for pixel optimization while discussing very small icons, and that's true, but it's a red herring. Interfaces should never rely on users being able to identify or interact with icons that are 16x16 pixels. At 64px, all of the icons seen in the article can be auto scaled successfully (in gimp, cubic transform): http://imgur.com/a/DOAyW
What we really need is to stop building hardware that demands 16x16 pixel elements, and to stop building interfaces that provide them. With high dpi screens, even character hinting becomes silly (or even without high dpi, I disable hinting on my 22" 1920x1080 screen because I like consistent letter spacing).
Pixel optimization experts may still have a place in the future, but it's likely in the same boat as audiophiles and $1000 HDMI cables.