Suggestion: Skaven climbing walls

I feel Creative Assembly missed an opportunity. Instead of Skaven using ladders to scale walls like all other armies, Skaven units should be able to climb up the walls without the aid of a ladder and perhaps even at a slightly faster rate than ladders. Maybe not quite "Starship Troopers" or "World War Z" zombie tower style but instead just waves and waves of rats scampering up the walls and in great numbers.... or maybe exactly like World War Z Zombie Towers...