No i dont think your right there. Since the connector only has a tab to lock it on one side. The piece is in the middle. It is in the way if you line the connector up to lock it. With regards to polarity the connector comes unpinned from morimoto so its deff no for preventing polarity mix up since you could easily do that yourself by putting the wires in the wrong side.Yes you need to do that to shut off PWM from the fogs. They may work but you are causing the LED voltage regulator to work overtime.
If you use the wires from morimoto you don't need to trim anything. The slots in the connector prevent folks from plugging things in backwards. i.e. + -> - and - -> +
You don't need a splitter just a wire.
Maybe you guys are talking about morimoto bulbs and nott the full fog light assemblies? ive installed couple of these and seen bunch more installed. Always required either use the splitter harness with the resistors (direct plug and play) or no splitter harness and Trim the middle of the connector then use alfaOBD to turn on LED mode so you don't get a bulb out warning.
Morimoto even list the splitter harness with the resistors as part of the package when you buy them? Not sure how you guys are getting them without the harness.