The dielectric grease does help keep the switch clean longer. The grease helps to keep water and air from causing corrosion of the contacts. it is easy to jumper the 2 red white wires at the switch for testing or emergencies.
As part of my winter maintenance I have just got in the habit of cleaning all of the handlebar mounted switches. Once you have done it a few times, it goes pretty fast.
I did not remove/disable my kill switch when I had problems with it, I still want that shutoff option there in an emergency.