Do you have any idea how many polygonjs are required to DO a human face? And NOT have it look brain damaged? (no offence intended to anyone out there)
At least they made the attempt with the in-game NISs, others might have switched to actors (which would have cost more, and the characters in the cutscenes wouldn't look anything like the ones in game) or even just used subtitles.
Sure it looks funny, but I play the game for the gameplay, not to complain about how unrealistic the imaginary faces look...