I enjoy the flashlight scheme as it is.
I've read about people cranking up the gamma.
People flying through on God-mode, modifying config settings to give more power to weapons or armor...
This game is easy as hell and I'm surprised so many people are having difficulty with it.
These little annoyances like having to switch between flashlight and weapon quickly adds to the difficulty and realism in my opinion (not to say duct tape isn't realistic).
My one and ONLY complaint of Doom 3 is that I wish they would have made it a little more difficult, along the lines of maybe Far Cry.
The difficulty in Far Cry brought additional tension to the game experience.