Feudal imperial and italian lists - dismounted knights

Playing feudal age in our club right now we noticed, that the feudal lists especially Imperial German 1150-1340, papal and silician list from EI5 do not allow to field dismounted knights.

Since almost Every FP comes with Long spears, we obviously thought about having an infrantry option to fight against the big infantry blocks. Dismounted knights would be an interesting option.

Since crusader lists and later medieval lists have these, I wonder, what was the reason for leaving these out. I guess it is the big social difference between knights and peasants during the feudal age which is to be represented here?