Responsive design is something that an be tough to pull off. You can’t just take a site and squash it to Responsive. The change takes place at a content level, an information architecture level, a development level and a design level.
Take a large image for example. In a responsive design, a mobile device will have to download that entire image. Not too great for smartphones with slower connections and with users paying for their data. Just because you can use the latest WebGL, CSS3 doesn’t mean you should. Browsers, devices, and OS’s all have their own quirks. We need to put the user first and make our websites future friendly.
The Filament Group is making some huge strides in doing responsive design responsibly. If your into code, check them out: