Why the need for mobile friendly site?
There is a significant number of searchers now accessing their diet of websites on mobile devices. Bad news the team at Google have tinkered with their algorithms.
If your site is not mobile-friendly. That is a site with a responsive design, then sorry expect your Google ranking to go down even if your information content is A1.
Mobile friendliness determines your Google ranking on their search results page. Mobile optimised sites experience high search results.
Thousands of searchers using their mobile devices have a good argument. Why should they suffer misshapen graphics because they prefer to leave the desktop at home and use a smartphone, or tablet?
Read Google Blog at http://googlewebmastercentral.blogspot.co.uk/2014/11/helping-users-find-mobile-friendly-pages.html. You can test your site to see if it is mobile-friendly by clicking on Am I Mobile Friendly
Read full article by clicking on mobile friendly