Are you still not sure? Google has also announced the Accelerated Mobile Pages Project, also known as AMP. While this initiative is still in its infancy it is coming soon and something of which you should be aware.
Mobile searches surpassed desktop searches in 2015. If your site is not mobile friendly you are certainly losing traffic, search results are being impacted negatively, and you are likely losing sales. Ensuring that you are ready for mobile site visitors should be an essential part of your digital planning.