Yet another factor:
The core engine may be capable of relatively fast acceleration, but if the acceleration is controlled in the traditional way - via a 3-D cam - one engine may wind up faster than the other, with possible Vmca or Vmcg issues arising.
And so FADEC can now be programmed to follow a "N-dot" logic, requiring the fuel rate be limited to that necessary to just meet cert accel requirements, and no more. Advantages: No yaw as thrust is advanced, and lower peak temperatures in the turbine.
(N-dot is the rate of change, in rpm/second, of rotor speed)