[DustyPorViva]

People like to feel that the game they are playing is responsive. Clientside HD provides just that -- when you see a player and you hit them, they are hurt. It responds(though this reflects the script itself).

Serverside HD is quite the opposite. Instead you must hit where the server knows the player is instead of where you see. That is counter-intuitive to what a game should be trying to accomplish. Responsiveness is very important to good controls and presentation.