Your Customers are Using Mobile Devices: The number 1 most important reason you need a responsive website is that your customers are using their mobile. 65% of all web trafficis done on mobile devices.
Make it Easy for Customers to Contact You: The more convenient it is for customers to reach you, the more likely they are to do it. Having a mobile-friendly website means that your email address and phone number are easy to find and clickable.
Google Wants Mobile Websites: Google has clearly indicated its desire for mobile websites. Websites fashioned for desktops do not deliver a good user experience when accessed on a Smartphone