>This will not let you install privileged apps though since they have to be reviewed.

so even Firefox OS is a walled garden? Telcos controlled what can be on your phone, Apple was able to wrestle them and overtake that control - control means money. Google follows the suit, forcing their in-app billing etc... Why would Mozilla support that ugly ancient "tradition"?

Safety. If you don't have restrictions, you get something like Windows/os x. Everyone can install anything they want from any source and that is also what makes Windows/os x much more vulnerable then Android or iOS. Priveleged apps are special applications with more permissions then normal apps, for example they can access the sd-card, while normal (web-installed) applications cannot. For more information you could take a look at: https://developer.mozilla.org/en-US/docs/Web/Apps/App_permis...