RWD is used to make the web better on small screens but what about big screens? The majority of TVs sold these days are large screens and TVs are still the centre of family life - we watch more hours of TV than we ever have. We are also meshing - we are using other devices at the same time. The TV is part of a larger ecosystem.
There are all sorts of ways to get the internet on TV - seven million households have a means of doing this. Smart TVs only make up 7% of this, it's mostly through games consoles - 53%.
How do we design for TVs? User input, device output and user position - find the intersection of these. It's different from desktop and tablet.
Users are likely to be about 10 feet away from the screen so you need to make things bigger. Small text is fine close up - to keep the same perceived text size as a smart phone you need to double the size of the text. TV manufacturers have changed how their browsers display their viewport - 1080p could actually be 800x500px. They are more like tablets than mobiles or laptops. Screen size doesn't tell you anything about where your site is being displayed.
TV remote controls are complicated enough without having to browse the web with them - the D-pad is the most common controller. Second screens are becoming the main inputs. Voice input will come along. Assume there's a D-pad and everything else is a bonus, or rather a problem. [I disagree, layered input can be done with some thought.]
The problem is that people find that browsing the web on TVs is slow and annoying. 2013 Smart TVs are about as powerful as and iPhone 3GS. TV browsers also score very low on browser feature support - some don't even run the browser benchmarks. The average lifetime of a TV is seven years - this is a new browser graveyard. We make the web on TV by bolting on add-ons. We use the TV as just a screen.
Is it possible to design for all devices? Maybe responsive design isn't the best thing - TVs are very different. Some sites have a 'big screen' mode that has to be activated. [Or we need to change the way we approach "desktop" design.] Responsive, content-driven sites work well. If it's easy to read on a small screen, it's easy to read on big screens. User agent sniffing often puts TVs in the wrong category. Screen size doesn't give us a complete picture of what we need to know to design an appropriate UI. The TV media type should be able to fix this but all devices respond to screen - this is our own fault, we only use screen. There are no features we can detect for a TV and user agent sniffing doesn't work. Couch mode is a user triggered setting that changes the base font size. We should be defining our dimensions in em not px.
The next generation of consoles are looking to address some of the practical issues. Maybe all we need is something like Chromecast that does screen sharing but it still doesn't solve the problems. Wearable technology, second screens and other things in the future will make this more complicated. We can't provide all the answers for our users - they will have to provide the context. Solve the problems we can solve, when you can't then ask the user what to do.