While I do agree with what everyone says about the flashlight I found it to add to the environment creepiness. I got bored a added the hack to brighten the rooms up (yes, they exist. Can't remember where just use google) but it took away the great pop up moments, for example:
I'm walking down the hallways... I can just barely see the ghoul up ahead, he sees me, I switch to my assualt rifle (or whatever), "HOLY CRAP! where did that pinky come from!"
I'm walking down the hallway.... Oh look a ghoul BANG! (I didn't even need to change my gun because the flashlight is useless with the hack), oh look a pinky in the room beside me BANG!
It just kills the adrenline of having to panic to get your gun out quickly and fill those creature with lead (or plasma.... or grenades..... or french fries <----- Got a little bored here). But the environment darkness also helps us feel like we're in a hellish Mars base.