Yeah, they could have jazzed up the story, narrative or what have you, but at the end of the day it's a shooter. Shooter-fatigue could have something to do with it:
Of the 17 games (christ) that I've finished this year, 7 were shooters, 3 RPGs, 4 Platformer/Puzzlers, 2 Other and 1 Sports.
I don't even like shooters. Or platformers really.
Dead Space 2
I am Alive
STALKER: Shadow of Chernobyl
Mass Effect 3
And Yet it Moves
To the Moon