There are many reasons to mention. Here are few of them:
Nowadays people use more mobile devices than laptops and desktops combined. I bet you saw people using their mobile even when they sit in front of a laptop/desktop. We use it even when we have drinks with friends, watch TV or go to the toilet.
Statistics show, that if your website is not mobile-friendly a visitor leaves it right away with a really low chance to return. While if your website is a mobile friendly you have a chance of 74%, that the user will come back to visit your site.
Due to the new policy of search engines like Google, Yahoo or Bing your website will be downgraded in their search results, if your website is not mobile-friendly. What makes it worse is the specifics of mobile users. Unlike desktop users mobile visitors will never go lower than the top 10 results of their search. That means if your site is not in the top 10 results of the mobile search you can hardly expect more customers to come to you via Google.
Mobile visitors are more valuable for your business than desktop users. A simple fact is, that mobile visitors are way more likely to make a purchase decision. It can be explained easily: Mobile users are users of quick decisions and actions. Once they open the browser on their mobile, they already know what they want go straight into action once they’ve found what they are looking for. More than that, Amazon recently revealed, that the average purchase done with a mobile phone is bigger than by desktop, because people tend to behave more spontaneous on mobiles.
Not having a mobile-friendly version can harm your brand and image. The surveys show, that if users don’t find your website mobile-friendly they don’t just simply leave it – with the impression that your company cannot serve them properly – they won’t even come back to your site when they will be in front of a desktop.
Mobile adopted websites can use the mobile phones hardware capabilities to ease the communication between you and the visitor/customer. With one click on a proper made mobile website a potential client can call you, message you or find the fastest way to you by using geolocation.