I can't speak about the design or operating characteristics of the MC plugs but in general one has to think the company building the engine should have the best plug for optimum performance, fuel economy etc etc.

I've read somewhere and cannot find the thread again that mentions MC plug threads are cut a bit differently than a long ago "standard" thread used by most every USA engine manufacturer. It was easier swapping plug brands and often times did in fact provide better performance. I gues it makes sense now to use the MC plugs not only for the more compatible thread configurations but time and time again we see someone whose switched brands only to suffer with a loss of something in these modular motors.

Sure the newest, latest & greatest thing might be attractive but in the end seems MotorCraft wins every time!