I use Stack Exchange on my phone a lot... and not just because it's my job. For the last couple of years I've switched between the iOS app, mobile site, and full site whenever I was using the site while mobile, particularly for moderation purposes as the app doesn't allow much in the way of moderation.
OK, to be honest, I didn't ever use the mobile skin much, instead zooming and scrolling around on the full site on my tiny screen, complaining every time a link was too small for my fingers to tap easily. Despite that, I still would have used this even before the responsive design. The mobile skin just doesn't do much for me that I couldn't already do in the app.
Now that we have a much more responsive site, it makes sense to allow users who prefer the new responsive view to set that as a network-wide setting rather than making them scroll to the bottom of the page every time they visit a site in a mobile browser.
What does it look like now?
Mobile users are shown the mobile skin by default. They can switch to the full site view by scrolling to the bottom of the page and clicking the "full site" button in the footer. Depending on the page they're on, this may take a lot of scrolling.
After clicking on "full site", that choice is retained for that site alone through a cookie. Subsequent visits to that site will default to full site view until the cookie expires.
This process must be repeated for each site as there is no way to choose a default setting.
What could it look like?
Registered users could have a preference on their site settings page that allowed them to indicate either the mobile skin or full site view as their default mobile view. Any time they visited a Stack Exchange site, they'd be shown it in that default view, across the network, as long as they are logged in.
The mobile/full site link would still exist in the footer, allowing users to switch which view they're currently using and still setting a cookie when that site's preferred view was different than their default choice, overriding it for that site alone. This allows users to view selected sites in the view opposite their default setting if they choose. It also retains the on-page access to switch views on demand.
I'd really love having this as a user setting.
But, wait... is the mobile skin even going to be around much longer?
All this assumes that the mobile skin will be sticking around for a while. One of the initial plans for responsive design was to retire it once the entire site was responsive. From Ch-ch-ch-changes: Left nav, responsive design, & themes :
Once all our pages are responsive we plan on doing some additional work to make sure everything works great on phones. At that point we will retire the mobile skin.
There's little reason for us to spend time creating this setting if the mobile skin is going away soon. At this point, we still have many pages that need to be made responsive including user profiles, the review queues, and all of the pages associated with moderation. On top of this, we've got some work to do to ensure the pages are optimized for small devices.
I don't get to make these decisions - really, that's for the best - but depending on the planned timeline for full responsiveness, maybe we can find a solution to this.