Most games doesn't try to portray a realistic FOV. It's typically within a 80-100° FOV whereas a realistic FOV would be 30-50° (depending on your display size and distance from monitor). But of course that is utterly horrible to orient yourself with that much "zoom" (but it's the only one that produces the true sense of perspective). With triplehead in front of you (not angled), you'd have a 90-150° FOV (with my setup I measure approx 100°), and this doesn't produce any visible stretching at all (since it's pretty close to the fake used FOV that games actually use).
In order to obtain near eye FOV of around 160-170° on an angled system, it will produce these gross stretching as long as the projection comes from an oblique angle. In order to get non stretching, the side monitors would have to be be separate cameras looking at respective direction, but that is probably not as trivial to support. But that introduces other distortion artifacts, like bending inwards at each monitors edge, increasing with wider FOV.
Personally, triplehead makes me more dizzy than increase my situational awareness, as long as normal game FOV are used. And when using "zoomed in mode" that creates realistic FOV, I miss too much information from the vertical.
And no, there is no need to make this game try to reflect realistic FOVs.
Correct me if I'm wrong, but for a game that isn't designed with multiple displays in mind, wouldn't you have to manually change the FOV angle? I know this can cause some weird effects (like floating arms) if you go out of the FOV range intended by the designers.
Anyway, I'm staying away from multi display gaming until some good, inexpensive ultra thin bezel (no more than 1-2mm on the sides) monitors come out. I wouldn't be able to stand having two big vertical strips of black down the image.