Mini Box Clarification

I currently have Cox TV Starter and I am confused why we would need the new Mini Box. Going directly from the wall to the TV we receive 16x9 HD broadcasts for all major networks as well as local PBS, The CW, ION and several others channels. This says to me we are already receiving a digital signal (not analog). I understand we may lose stations that we currently receive in 4X3 aspect but why all stations?