Comment by OhMeadhbh

Assume you're a government agency. Assume you want to install software that isn't in the AppStore. Perhaps some software you wrote yourself. Sure, the security of the system should be based on keying material, but you still don't want the general public to know you're installing Coup d'Etat 2.1 on your devices. And you don't want Apple to know that you're installing Corporate Fiscal Surveillance 1.1 on your iDevice.

It would be nice if you could maintain the many security features that DO exist while at the same time installing apps on your devices you want to install without having to have them blessed by Apple's dev CA.