@Felthry I think this is a symptom of the bizarre way video game voice acting is usually done. The voice actors rarely get to read a script, interact with each other, or have any real context at all. A line flashes up on a screen, they read it three times, repeat.
Picked up on this from interviews with Ellen McLain (GlaDOS, Portal) and Jennifer Hale (Shepard, Mass Effect).
@Felthry No idea. The actors don't really like it either, as far as I can tell.