Because at Infinity Ward we make a really clear point to make sure we only upgrade the things that are necessary for driving the things and the gameplay experience we want to push for that project.
However, there is certainly a use case for the PadFone Infinity, and we are long past the point of the graphical power or screen resolution of the phone part being a problem when plugged into its tablet battle suit.
At this point, Hollywood agents were brought in to try and bring Infinity Heads Jason West and Vince Zampella over to team EA. They flew them out on private jets for barbecues and other get togethers with EA staff, when it was well known that they were still under contract for another two years with Activision.