I'm not sure 75% of the power would be wasted in the resistor. This discussion is neglecting the total impedance , including the reactance (inductance) of the windings in the coils.
Regardless, we want the current in the coil primary windings to build to a certain level, then cause the magnetic field in the windings to collapse instantly to produce the spark energy. The spark energy comes form the collapse of the field, not directly from the primary current.
If the current builds to the desired level with resistor in place, then life is good.
BTW, the value of the condenser has an effect on the generation of the spark with a given coil.
BTW there is a previous member on here that FRIED his stock ECU trying to run Ford COPS with his stock set up. He had to swap to an ignitech after that. Things still needed to be swapped around to make the Ignitech work with the ford COPS.