Many people equate usability with simplicity. Their premise is, "If we just make it look simpler, people will use it more." Simplicity is the current trend in Web interfaces, going back to the Google homepage and forward to Web 2.0 interfaces like Twitter and Basecamp.
If it's not right for your business, feel free to buck this trend! People do not buy simple, they buy feature-rich. Recall also the first commandment of usability and know your audience. Products built for novices can be simple, but the same interface may turn experts off.
If your audience leans towards one end of the novice-expert continuum, that must guide your interface design. Experts need interfaces that are powerful but complicated, while novices need simple, step-by-step interfaces. In between is a broad middle ground of users who are unhappy to sacrifice capability for ease of use.
In general, you want to find the correct balance of simplicity for your interfaces, by experimenting, testing, and building to your audience. Realize that in most cases users expect a certain learning curve to achieve competency. Finally, a balance between ease of use and features also can help you maximize revenue.