There's still no official word or reports yet on whether XIM or Cronus controller-spoofing mouse and keyboard adapters will be banned as a result of these policy changes, but manufacturers like Brook Gaming who build unlicensed, but fair adapters for fighting game sticks seem to be caught in the dragnet. We'll be sure to update you on further changes.

I think XIM and Cronus are the reason they're doing this, especially since the main games on Xbox are shooters.

Cronus allows you to run scripts which give you an unfair competitive advantage, from using exploits and humanly impossible controller inputs to fire weapons ultra fast, to removing weapon recoil, to going auto-prone when you fire your weapon, to quickscoping, to other things.

XIM on the other hand lets you plug in a mouse and keyboard. While this allows you to play games on console that otherwise don't support M&K controls, it also gives you serious unfair competitive advantages by making the console think you're a gamepad player whilst giving you superior M&K controls and aim assist at the same time. With a XIM device you can go seal clubbing in console-only lobbies.

My other hypothesis is that they want to safeguard their console from firmware exploits that could bust the security of their console wide-open and allow for software piracy.