The number one reason is to create a positive user experience. Whatever the purpose of the visit—buying a product, reading a review, gathering contact information—it should be as easy for the user as possible. With a responsive website, the user experience is dramatically improved because the layout of the site is optimized for the specific device in use. By reducing the need for the user to scroll and pan, information is easier to find, and the user can focus on the purpose of the visit instead of fumbling through a site that is difficult to use.
In early 2015, Google announced a change in its algorithm that will impact all searches done on mobile devices. Websites that are mobile-friendly will receive a higher ranking in mobile searches than those that are not. This is big news for all websites, considering that approximately half of all Google searches are done on mobile devices.
In order to help maintain your website’s search ranking on mobile, and help drive traffic from mobile searches, Google recommends using responsive website design. This will not only ensure your website is mobile friendly, but it will also help avoid having your website’s search ranking demoted during mobile searches.