Pax, not to generally disagree with what you said, but I would be using the light on my Glock only if I had a reason to use the Glock in the first place. I have 2 uber-tactical flashlights next to the bed, and the Glock is in a secure area not in reach. I would never consider using the Glock light to check the breaker panel for a thrown breaker. I also have a tac light mounted on one of my CAR15's. Same use. If I need the rifle in the dark, then I will probably need the light too. Just a FYI, I live in an unincorporated residential area.
As always, each person has to make their own descisions. I added a light to my pistol because I had to clear the downstairs area of my home one night. Fumbling with the flashlight and pistol in a stress situation is compounded trying to turn on lights inside the house. I personally will keep that particular pistol "lighted".