So I conclude, that the problems come from the fact, that kam is a defensive game. The defender has the advantage that his archers shot first. Always. The attacker has a disadvantage, regardless of towers of units.
Well thats nearly in ever Strategy game like this and also in reality, why the defender shouldnt have an advantage.
Like you already mentioned you cant compare knights with towers, while Knights are like the most expensive troops

The problem is that often you see bad players/beginners that have like 1/4 the army of you but have like 20 towers, because of the small costs. So everyone is able to rush many of them. The best possibility to counter that are the catapults, because you havent any other ways to stop towerspaming/place towers at bridges. The
only problems that a towerspammer could have:
-Run out of stone
-No food for recruits
However you won´t find one single player who has no stone on these mp maps from today and when someone has like no army but many towers,he also hasnt often foodproblems. So there is like 0 "punishment" for the defender.
I don´t agree to your point to increase the Towercosts for sth like 3 ironbars or sth like that.
There is also no point to set sth like a "max. tower/player setting" (There were already discussions about a mutator or so), because it depends from map to map. Until you need like on GoldenCliffs bottom-right corner lets say 8 towers at least(playing top vs bottom), the same number of towers on cursed ravine would make it impossible to attack this player. SO I can´t see any normal way to get out of this problem really.
Btw the siege on TPR was implemented to have a strong support and get a little boost for the attackers. They were OP because they could kill like 3 units at one hit, but the idea to destroy only towers/buildings with that is no way, not to try it in my eyes. I still think, that the defender should have a little advantage in comparison to the attacker, but not that big like it actualy is
