All the TW games actually:
The In-Game 'RADAR'.
Now many people have opinions on the usefullness or just how darn handy it may be...but really folks, if there is one thing that totally destroys many aspects of battle tactics for both sides (especially in MP play) it's this CA constant throughout all the TW games. The Radar destroys any chance you have of making suprise attacks or flanking hoping your opponent has not seen the move including the setting up of ambushes. It's also a 'greedy' aid in chasing down fleeing foes and has no place whatsoever in ancient/medieval or Napoleonic wargaming.
Personally I think it would be a great idea for ALL the 'MOD overhauls', to erase it from all our screens.
However, no doubt players have their own reasons for wanting to keep it. Perhaps it's just something players have gotten used too and they have not even tried playing without it! If not - may I take this oppurtunity to strongly advise they do try it, because I know they will find their battles refreshingly appealing; especially of course in MP play.