I don't understand why you think permissions need to be agreed means that the apps are unsafe. Unlike Android, all apps are checked by Microsoft before putting on the Windows Phone Store and you cannot install apps outside the store.
Malwares cannot make any changes to the system, because it is not from the Store and it will not have permission to affect your phone.
For example, a calendar shouldn't need camera access
aabbccdd92 發表於 2015-5-7 22:47
The apps have rights which it does not actually needed does not mean that it is unsafe to the system. It is just unsafe to your privacy. You can choose not to install if you disagree to grant those unneeded permissions.