How is it bad to have dead bodies in the core for more extended time for server performance?
If you extend it from 1 minute to, let's say, 5-20 minutes (depending on current server performance?), it'll be pretty informative to know, if any combat happened around before. So e.g. corner with the sneaker ambush killing bluesuites will be obviously dangerous, door choke-points will be more obvious to avoid and cool battlefield will look properly just because there're remains laying around.
Could be done if after 1 minute replace the player's critter with npc critter with the same skin, I think.