IPhone :: Password Protect The 4 Switching Off Button?

This would make it easier to track the phone in case stolen, And also have the time to remotely remove data in time, before it goes out of reach who knows where and what purpose?I understand the phone would eventually switch off when no juice on battery, but I hope Apple engineers would code this feature as it would make it harder time for criminals. My friends phone was stolen yesterday, and It was protected by a four digit code, and a bundle 24- months plan phone. So no one should be able to use it as a phone, or can this be overrided? Anyway, I wish Apple would make even more systems that would make it harder time for the criminals.

Info:
iPhone 4, iOS 5.1