I wouldn't call it worthless. It's not for everyone. I have one and have found limited use. For navigation it's actually easier and faster if a controller is nearby. If not, it is convenient to be able to then speak your way through. Of course talking out loud for general navigation probably isn't going to be, and hasn't become a big thing to do. If you "have" to connect it, hopefully it has been streamlined. With no motor, it should be much smaller. Also requiring less physical space will help increase its use.
As for the Xbox 3 reportedly being underpowered compared to the PS4. That is the interpretation of PS fans. Most centered around GDDR5 vs. DDR3. While all things being equal GDDR5 is faster, and more expensive, there are many things that can be done to erase or eliminate the modest real world performance gain. And talking 8GB, it could result in a significant console price difference. Cost means a LOT these days.
Going solely by the leaked specs, the compute power of the Xbox 3 is 1.23 TFlops, the PS4's is 1.85 TFlops. It's not really interpretation, it's based on the numbers we have so far. That's pretty much the difference between a model range in PC GPU's. AMD 7770 vs. AMD 7850. or Nvidia GTX 650 vs. GTX 660.