Usability and the utility, not the visual design, determine the success or failure of a web-site. Since the visitor of the page is the only person who clicks the mouse and therefore decides everything, user-centric design has become a standard approach for successful and profit-oriented web design. After all, if users can’t use a feature, it might as well not exist.

http://www.smashingmagazine.com/index.php/2008/01/31/10-principles-of-effec...