Disabling stolen phones

You can certainly let Apple know what you'd like to see here:

Product Feedback - Apple

If you set up Find My iPHone on your phone, when it is lost or stolen, it is pretty well disabled. The only way to get past your passcode lock is to restore the phone. The only way to finish restoring the phone is to enter the Apple ID and passcode to which it is locked.

You can also report the phone stolen to your carrier. They will disable the SIM and add the IMEI to the stolen phone list.

"Why" questions can only be answered by Apple.....and you have posted to a user-to-user support support forum. We are all users here.....just like you. No one from Apple will answer.

None of the users here can answer any questions about "why" Apple does what they do or when they might do something.