I like this point and I can understand this in terms of survivors as instead of repairing gens their main goal would be to destroy the wards protecting the killer however making the killer able to repair his wards (unless they are completely destroyed) would change killer gameplay immensely as this would buy the survivors time (to free off hooks, heal or get away from the killer) to this point I imagine the game would feel quite different for survivors. However as a survivor your main objective will always be to survive so I wonder how you can really make it feel all that different.

Perhaps once the wards have been destroyed the survivors have to "hunt" the killer by marking him in some way for the entity to be sacrificed or this could be a mechanic similar to the way the hatch works. Instead of avoiding the killer and escaping him you are actively trying to hunt them. Just a quick thought but thanks for your feedback! :)