Mozilla's web app store debuts in Firefox for Android

Agreed. Another thing that matters is binary compatibility. For years we in the free software world tried to convince ourselves that binary compatibility didn't matter (Mark Shuttleworth explicitly disclaimed the idea of 'compatibility at the level of binary blobs'), but it does. Otherwise, third party 'app' developers have no way to be sure their work won't be capriciously broken by some later update. Miguel went into this in his blog post which you may have already read: http://tirania.org/blog/archive/2012/Aug-29.html