Clan Castle Defenders

Allow surviving Clan Castle troops to remain in the castle after successfully thwarting an attack. Any survivors go back to the castle to defend again. Many times i have watched my castle unload its troops just in time for a mortar ball or something to finish off the last few attackers and BAM! no more defenders even tho they hardly fought at all or in some cases never even fought. Let the survivors regenerate health to 100%, any that died during attack defense are gone

They allow troops that survive in defense to go back into CC, why don't they allow it for attack?