First things first: an author’s website, whether it gets much traffic or not, is foundational to your career. It offers readers as well as the media the official word on who you are and the work you produce.
If you blog, then it can also be a way for the public to engage with you. But mainly author websites help you shape the story surrounding your work—and ought to be found when readers go searching for you. It allows you to focus people’s attention and interest on what’s important to you—as opposed to what other sites might think is important.