If you remember Doom 3, you'll remember that the amazing visuals and creepy setting were ruined by two things: too much darkness, and those stupid "monster closets." Looks like id have learned their lesson on the latter.
To those who may not know what they are, "monster closets" were areas of a map where an enemy would be "hidden", and only revealed when the player "triggered" them by opening a door, or walking to a certain point on the map. It was cheap, and quickly became a royal pain in the ass.
So for upcoming shooter Rage (which is looking quite interesting), monster closets are no more. id's Matt Hooper:
[In Rage] when you're going to the RC-Bomb base [from the demo] to deal with the Shrouded clan they're doing whatever they're supposed to be doing. If they're supposed to be defending against you coming there, they'll be doing that. If they're just tinkering or having a conversation they'll do that. You will never see [a monster closet.]