The fact that it can be unlocked with a picture doesn't mean it has no security.
The main use case for phone locking is that you leave your phone in a cab, a bar or wherever else in public and someone picks it up later. That person isn't going to know who you are and have a picture of you. They're still prevented from being able to take the phone they just saw laying around and go through your emails, etc.
The main use case for phone locking is that you leave your phone in a cab, a bar or wherever else in public and someone picks it up later. That person isn't going to know who you are and have a picture of you. They're still prevented from being able to take the phone they just saw laying around and go through your emails, etc.