I agree with the OP. It would have been nice if the bodies stayed around a bit longer. I have trouble finding my loot in the high grass, not to mention that it can look pretty awesome when dead bodies are piled around you.
Constant spawning feels like a lame excuse to me, because I think constant spawning is itself pretty lame. Though I suppose there may be circumstances where it's appropriate, but even then, I don't see why the bodies can't stay around a bit longer than this.
Medieval Total War 2 can easily deal with hundreds of soldiers on the screen, and keeps their bodies around after the die. Why would a few bodies be such a problem here? Well, I suppose TW2 has a lot more detail in the scenery: grass, leaves, etc. But in comparison to the huge numbers of polygons already there, do a few bodies really matter that much?
And if the body count gets too high due to constant spawning going wild, you can always remove the oldest bodies at that time, rather than immediately after death. And then please fix the constant spawning.