There is a thread for feature requests.
The same principles apply to a desktop and mobile. If your desktop view is complicated in any way, its not a good design. Start at the lowest built in breakpoint for Foundation or Bootstrap. It will be a tablet view, 576 to 768 pixel. It will be easy to create a design that collapse down to 320 px - even if not refined, and using the same principles you already know, have the design flow up. If you know you are going to have 4 cards across on a desktop, and 2 on mobile, then you make the columns, or give them the appropriate classes, sizes or flex basis at the built in breakpoints. If your webpage is so complicated that a desktop can not easily and visually move to a tablet or the other way around, you have gone off on a horrific tangent in usability design and need to rethink it. What happens if someone takes your website, and miracasts it onto a 80" inch television - are you just putting in failsafes in cast that happens (thus designing "desktop-up")?
You need to understand what these Frameworks are. Coffeecup is now making RSD to use the Frameworks Foundation and Bootstrap. The framework they created Coffeegrinder, is not going forward beyond what it already has. I don't know the decision why, but I will guess because companies like Zurb and Twitter give out their frameworks for free use, and makes its hard to compete free.
Foundation and Bootstrap might have been desktop down at one time. They are not any longer, and they never will be unless people get sick and tired of using mobile devices and and designers stop caring much for mobile applications and websites. There are other frameworks, and new one being made, and they also are mobile first.
Designing mobile first, is different, but it is not hard, and it is better for all sites of all sizes in the long run. You need to read these and understand why this is a trend - a trend start a long time ago and actually has pretty much stopped trending, as it is the way frameworks are at now. Even RSD 1.5 had options for mobile first. I believe people get stuck in a desktop down approach because its the first way they learn, and when learning about responsive they are tought how a desktop can be made responsive.
http://zurb.com/word/mobile-first
http://www.webinsation.com/why-should-i-design-for-mobile-first/
http://bradfrost.com/blog/web/mobile-first-responsive-web-design/
Once content is structured, the first context to pipe the content into is the mobile web. Why start here and not the desktop? The mobile web is far more restrictive, eclectic and unstable than other contexts. The mobile context is hazy. Is the user on the go or on the couch? Are they on WiFi or EDGE? By first creating an experience that prioritizes a worst-case mobile scenario, you ensure that your users will be able to accomplish their goals despite a lot of factors working against them. In short, if you can support the mobile web, you can support anything.
Scaling up from the mobile context versus scaling down from the desktop context ensures that your message, content and functionality remain intact as the screen real estate and connection speed increase. Scaling down runs the risk of your core message and functionality getting lost by the time you squish it all the way down to the mobile context.