I think the sprites are like this because when AH came out, it was really pushing the graphics engine / graphics card hardware for the time and it was a compromise of performance.
With my current PC runnning 1900x1600 at 4X AA with 16X AAF at 40-60 FPS, there is probly scope to have more accurate machine gun hit sprites.
What I would request to see, is that my hits dance all over the area I hit at 1/60th of a second duration. That would be more like the guncan footage I have seen to an extent.