The biggest problem with Siege Warfare is that it shouldn't exist according to the rules. Wizards make it somewhat unlikely. Teleportation Circle automatically negates all starvation problems. Wizards can stand on the Battlements and Fireball your Siege Engines for fun. Walls are easily passable/destroyed. And superpowerful individuals (not to mention Cloudkill) make all the level 1 Warriors obsolete and heavily casualtied.