Honestly I don't think we need an app. The site already changes to a mobile-friendly layout on phones - the only downside is that is doesn't work offline.
You can sort of turn the site into an app on iOS though. On Safari, there is a function that allows you to put a shortcut to the site on your home menu, but it is just a shortcut and works no differently to when you open the site manually in Safari. It is the closest thing you'll get to an app though.