It is important to understand that the core strategy for most websites can be summarized as a formula, where
Visitors * Conversion Percentage * Order Price = Revenue
This could be translated to sites that are intended to produce leads.
Usability dramatically effects the conversion percentage of a site. Therefore, proper planning and design of the navigation and usage models are important to the bottom line of a website.
Consider the following example:
A designer decides to be “bleeding edge” and put all of the menus for navigation of the web site under a single, unlabled, dot. Visitors come to the site, can’t find anything, and leave. Never make your visitor have to learn how to navigate your website.