meanwhile Gandalf makes a cavalry charge down a waaaaaay too steep hill towards the aforementioned pikemen
We need to resist the hegemony of the wizards, these guys clearly have no business making decisions for the rest of Middle-earth
The Battle of Helm's Deep is full of very obvious errors. There is an awesome Dutch historian, Roel Konijnendijk, who trashes movies for fun that talks about it:
https://www.youtube.com/watch?v=xPGdOXstSyk
My favourite one is when they are shouting orders to eachother. There is no way for the Elven archers to hear Aragorn's commands, or for Aragorn to hear Theoden's fallback order.
Maybe the walls finished constructing while he was sending his troops across the map. Happens to the best of us.
Pikes beat horse dudes, Rohan has horse dudes. Unbeatable logic. Dev did not code for horse dudes having different armour off horse.