Kristofer, this is a good question.
The reason the Xperia Play loaded up the mobile view and the others didn’t is because it’s the only one that identified itself in a way that the website understood to be mobile. But you make the point that the others would have benefited from this experience too.
Some of the consoles have in-browser options to optimise the site, like the Wii has a button that linearises the whole page, and the 3DSXL has automatic text wrap. I think these are a good solution because even if we put in media queries, the screen width is the same as some desktop computers. User agent string detection isn’t a good idea either because they lie, and they don’t prepare us for all the weird devices that have yet to come out.
What we can do at the moment is make our sites easier to use overall and consider how people will interact with them on a range of devices. Things like making click areas bigger improve the experience for not just the console, but also desktop and mobile experiences. I think this has to be considered from the design stage to be effective.