Bob,
The sharpening of the electrode provides a stable, hotter spark at a fixed location every time. Electric charges love sharp edges so they can ionize the surrounding gas and make a spark jump.
Whether this provides more power or not remains to be seen. It does however reduce the voltage needed for a spart, and make the spark more consistent. It also increases the available top end rev range, because less capacitor charge is needed (In CDI) or dwell in contact breaker ignitions. That is why pure racing plugs often have a very thin central electrode. For sustained spark energy at high rpm.