With bright banners of red, gold, blue, and semen white, the proud combined armies of Occitan and Hero Party displayed themselves before the Walls of New Rindyar. Among the men there was confident banter about how their magnificent army was going to rid these lands of the Frisian invaders and their Norse friends. After all, God Wills It.
Inside New Rindyar, the mood was much different. The display before the castle was one which struck awe into the hearts of all the defenders. How could they hope to stand before such military might? Such thoughts were in the heart of everyone of the brave defenders as they prepared to meet their end to the massed ladders and catapults of the Hero-Occitans.
One thing that neither side took into account though was one crucial fact. New Rindyar is a castle. Now the purpose of a castle is to be nigh-impregnable and to cost any army which dares to assault it grievous losses. So, "instead of direct assaults, besieging a castle was more cost-efficient and effective. However, depending on the castle, sieges could last from a few months to years. The siege of Donnington castle lasted from July 1644 to April 1646." A historical incident which proves this point is the fact that "in 1403, a force of 37 archers successfully defended Caernarfon Castle against two assaults by Owain Glyndŵr's allies during a long siege, demonstrating that a small force could be effective."
New Rindyar indeed proved the point that assaulting a castle is SUPPOSED to be extremely difficult. If an attacking army wants to take a castle by storm, it has to massively outweigh the defenders in both men and material as castle walls are DESIGNED to multiply the garrison force by factors of ten or more.
So, instead of a direct assault, most castles were taken by sieges which either starved the castle out (made it run out of gold) by cutting it off from reinforcement, or by forcing a field battle. In addition, attacking armies would generally ransack the countryside (take easier to assault fiefs) thus weakening a force in a castle to the point where it has to fight in the field or dissolve in its castle.
So to those of you who complain about how terrible the assault was, I agree with you. That was an utter bloodbath. However, I think that it definitely demonstrates the point that castles are supposed to be fortresses which are extremely hard to take. If you want to beat the army in the castle, you either need to lose thousands of troops doing it, or be like the best generals in history and force a decisive engagement in the field by bleeding the enemy out to the point where they can no longer sit in the castle. After all, a force can only do so much from behind its walls. It must come out eventually and it is up to an attacker to make them come out.
tl;dr: Castle assaults suck. However, I believe that they should continue to suck as the role of castles is to make an excellent defensive position. This is balanced because even if you have a good defense, you can only do so much from behind your walls while your lands (and thus wealth) are sacked and burned and your traders (again, wealth) are destroyed.