The immersiveness of the FPS perspective simply begs for realism, and unfortunately the last big game that tried to distance itself from this trend turned out to be crap.
If you want fantasy and originality now, pick up an RPG.
BTW, I wouldn't call Deus Ex 2 original. Revolutionary, but not original. I was impossible for me to play the first game without picking up on the System Shock 2 and Thief influences.
"Nothing livens up a robotic hymn of doom more than an amazing pair of jugs." - Brak