There have been some simple FPS shooters like you describe, some "arcade 3d games". Do you know the "Serious Sam" series? Or what about the game, where you enter hell to defeat tons of enemies, I forgot the name of it.

A very new game called Legendary might be also that way but I did not play it so far. But I also realized that these games sell good but not exceptional good like innovative but still simple games (Bioshock is a simple game, you can shoot all your way if you like).

And I agree, that the feeling of the first Doom and the first Unreal is still different, better and unmatched. I cannot explain why this is the case. But the first Unreal was a perfect mix of fantasy and sci-fi, peace and war, action and exploration, magic and science. It was amazing. Later games did not reach this (except of the action RPG Outcast, but this was not very successful, dont know why).