So there is the part that this will ruin hard built structures but if u allowed cannon damage it would make it far more realistic (cannon shots didn't just disappear on impact with stone) and this would get rid of people hiding inside there houses until the raiders have left. so theres the point were people may over use this to greif bases that's why u add a fale safe like 4 shots every 30 minuets or something and it takes like 2 shots to destroy a wall this would control greifing threw cannons a bit more so I think this would make cannons more realistic along with making raids more involved too instead of hiding in a house and standing at a front door people can stand to fix a few walls.