One thing that struck me from your post is how monsters avoided the light. I would love for in a game like RE4 that you could find refuge in the light. It would intentisfy drama by making very close scenarios, where the player is forced to find the light. It can make some very scary moments. It is a great effect. The question would be on how easy would it be to complete such a system.

Not easy with moving lights, moderately difficult with static lights. The best example is Thief.

Getting a proper shadow displayed is hard enough. Calculating line of sight for a shadow is currently, as I see it, out of question. (given how current techniques work, at least)