At Pubcon Las Vegas 2014, Google's Pierre Far was talking about how important it is for Webmasters to get on with mobile site development. He demonstrated how the statistics show that mobile is growing rapidly, and importantly, that some markets are mobile only audiences. In other words, some audiences have mobile nly Net access, and no desktop.
It's not that you just need a mobile site, but that you might want to make sure your existing site is mobile-ready. on The Subject of Mobile Calls For Webmasters to "Get on With It"
I'm sure you've checked your site renders quickly on for the desktop, but it's worth considering the challenges for your site to render quickly, and effectively on a mobile system.
webpagetest.org
And, importantly, from Google's point of view, allow Googlebot to crawl css and javascript. Also member that Flash is not good for mobile.