What I think many programmers miss with "visual design" is that the mere "pixels" are the user interface. They are one the most important parts of an app. Done right they should make an app both easier to learn and more efficient to use. Conversely, it is true that design that over focuses on form at the expense of function can make for a bad user experience indeed. I'm neither a designer or programmer, but I rely on software to make my living, and the difference in quality between apps that have apparent feature parity is vast base on their UI.