The original AI War didn't have acceleration either, that I recall. A big part of that is to do with the coarseness of the underlying simulation, and the general processing requirements (read: huge), that keeps things a bit more abstract in the shooting and moving departments. Yep there would be sideways drift on big ships if we made their turning slower, but it might still look cool; hard to say, because sometimes they would drift backwards.
Keith, I do wonder if some sort of fakey concept of acceleration might make sense for really large ships? Basically kind of like gear-shifts, almost. I dunno, that's probably scope-creep.