Mobile is a hot topic and in the SEO world, mobile SEO is confusing and debated like crazy. So when you see Google post anything on the topic, mobile SEO 'experts' jump on it to debate it.
The latest Google post named Responsive design – harnessing the power of media queries talks about why Google likes responsive design. It was written by Rupert Breheny, a front-end developer at Google and he mostly talks about why he likes it on the design and developer side.
Google's Michael Wyszomierski, aka Wysz, shared his thoughts on why he likes it from an SEO and maintenance perspective on Google+.
In short, here are the three reasons he likes responsive design over specific mobile sites:
(1) Easier to maintain one site vs many. So having a design that adapts to the device automatically can save time and makes sure you have the same content for everyone. There are many who would argue mobile users don't want the same content. But the point about maintaining different content basis is a strong one.
(2) Responsive design doesn't have canonical URL issues and you don't have to worry about ranking issues, he said.
(3) You don't have to worry about redirects and he said that "many sites are terrible at managing redirects." Trust me, he is involved in webmaster relations, so he sees how most sites handle redirects.
Forum discussion at Google+.