This addition seems to be more about making them more amenable to being hacked up by MobileFrontend or Mobile Content Service than about actually making them friendly for mobile devices.
A better long-term solution, IMO, would be for people to work on using TemplateStyles to make the mbox templates responsive so they wouldn't have to be hacked up. That way people using the desktop site on mobile and people copying the templates to other wikis would benefit too.