• Google announced mobile SEO recommendations earlier this year (cue marketers and developers to frantically implement their mobile sites accordingly).
• Too many heard simply, "responsive design is the way to go", and didn't hear the important part about choosing "the best option to serve your users"
• Googlebot is able to crawl your website if you follow google's setup recommendations, mobile URLs are fine to use, and responsive design is just one option.

Google's official mobile SEO recommendation:

1.  Google recommends webmasters follow the industry best practice of using responsive Web design, namely serving the same HTML for all devices and using only CSS media queries to decide the rendering on each device.
2.  If responsive design is not the best option to serve your users, Google supports serving your content using different HTML. The different HTML can be on the same URL (a setup called dynamic serving) or on different URLs, and Googlebot can handle both setups appropriately if you follow our setup recommendations.

From the article:

Google did not just tell all of you to make your sites responsive. Actually they did, but that’s not all they said. At SMX Advanced, Pierre Far of Google announced something else as well.

Responsive Web design is Google’s preferred option he said, but only if it’s best for a site’s users. You may think this is trivial, but it’s not. Just ask the sites hit by Panda and Penguin how important paying attention to users is for sustainable SEO.