For the 2010 earthquake (which was at 3:30 AM) electicity went off in the whole city and I didn't have a flashlight handy in the room I was living in. The only luminous thing I had handy was my cell phone screen, and no, it doesn't help very much in complete darkness in a room scattered with debris and fallen-down furniture. I'd rather have had a flashlight.

For some definition of flashlight. I use the LED on my phone for a flashlight several times a week and a white screen just doesn't cut it.

* Your hike took a bit longer than expected and now you're coming back down the trail after dusk.

* There's a rustling noise in the bushes, is it a raccoon or a burgler?

etc.

This. I used mine on a long run into the mountains last year on holiday, left super early (5am) before the sun rose and it got unbearably hot. No lights on the dirt path we were running along so the iPhone flash worked a treat.