I don't really see the purpose of this. This will only create a fake feeling of lighting and safety, while still allowing monsters to attack you when you wander in the dark.
Also: imagine this on multiplayer, where a Player holding a torch can sneak up on you because he can see you while you can't see him.
I use dynamic lights(does what is suggested in this thread and its client side).Because of dynamic lights other players holding torches cast light(I have tested this on LAN , a vanilla server, and on a server with 170 something mods). So players sneaking up on you wouldn't be a problem if it was implemented right. Also being able to have a sword and torch is helpful for combat with mobs or players (I say is helpful and not could be helpful because I can and do duel wield a sword and a torch on my server).
Also, I support this idea.
EDIT: I see a lot of comments that it would cause lag. I use the dynamic lights mod(as stated above) and I have tested it on a laptop with a 1 core cpu and 2G of ram, a desktop a 2 core cpu and 6G ram (neither has a dedicated GPU) and a desktop with a 8 core cpu, 16G of ram, and a overclocked nvidia GTX 970 GPU. All of them still ran at the same average frame rate as before. I had smooth lighting on when testing it on the two desktops, the laptop sadly couldn't take it.