its very SWish, we arent called the rout for nothing. When the enemy is routed we keep advancing.
D. Eldar strike me as attack fall back and attack again, like the raiders they are.
UM: The enemy is routed. Good regroup and prepare for another attack.
SW: The enemy is routed. HAHAHA KEEP ATTACKING WOLVES! PURSUE THEM TO THE EDGE OF MORKAI/HEL!!! NONE SHALL GET AWAY!
Not saying that the rule isn't SWish, it's just that the Dark Eldar already have that rule in their Index, so I think Space Wolves should get something different rather than copy paste from their rule. so lots of armies share rules under different names. I have never liked counter attack from thematic approach you never see in the books or fluff. It's left over from 3rd where DA shot, BA assault and Oh what we going to with SW ah I know counter attack which never fitted the fluff.