The problem is that the whole "all doors close, light turns off, monsters spawn", or the lighter version of "door opens behind, monsters come from it", or sometimes "monsters teleport behind you" was the entirety of the gameplay. The first few times it made me jump, but then it just became boring. Pretty soon you could predict when it'd happen, too.
The other cheap trick was to make half of all maps so dark you need a flashlight, but make it so that you couldn't use a weapon while the flashlight was out. IIRC the very first Doom 3 mod was the one that fixed that, and it was called simply "duct tape".
