Yeah, there are surely 100 of ways to lock down the phone and prevent it to even be able to factory restore without entering the screen lock code.
Simple, Apple just have to allow iPhone users to link their lock screen code with their iTunes account, like adding I field in iTunes account which say enter "Enter your iPhone lock screen code to link it to this Apple ID"
My Apple ID is
[email protected]
Pass word is 1234567890
iPhone lock screen code is 1234
once some one steal the iPhone and enter a wrong lock screen code 10 times, another screen comes up asking for entering the Apple ID user name and password. If wrong Apple ID and password are incorrect 20 times then the system know that the iPhone is not with its owner, so the system lock down completely the iPhone until it's take to Apple store for unlocking. Apple will the unlock the iPhone BUT before returning it back to the one who brought the iphone it in, he or she will have to prove to Apple that the iphone belongs to him/her. He/she might not have a receipt of the phone (gifted by a parent etc...) but he/she should be able to answer few questions if the iphone really belongs to him/her. Questions like:
-when was the iphone purchased or gifted to him/her.
-naming 5 contacts name present in the iPhone contact book
-naming 3 apps present in the iPhone except the stock apps.
-name one mail address which is setup and be in use in the iPhone.
-Finally Apple will ask for that person ID card to know his/her full name (eg. Mr ABCD Xyz) and suggest to him/her that Apple will call back the most recent 3 phone calls and ask them if they know Me ABCD Xyz.
So basically if the phone is stolen it shouldn't even be able to become an iPod. It should be a complete useless iDevice for the one who steal it unless deciding to sell parts of the iPhone.
This is just one way of completely locking down iPhone in case it got lost or steal by someone.
I strongly believe that there are better than this, I just don't understand why Apple refuse to go down that road.