It has nothing to do with the horse, and everything to do with the AI. If the AI knew how to effectively use spearmen, there wouldn't be ANY cavalry at all :p
As for his argument being invalid...
Take that master crusader, now but him up against an Einjehar (Or however you spell the bloody thing)
On field, the cavalry will crush a single one. En masse, the cavalry will get clumped up in the mass of axe men and cut to bits. Cavalry is MEANT to be over powered, or else nobles wouldn't ****ing use horses
Now, put those master crusaders in a siege assault, then siege defense against those Einjehars and watch them get torn to shreads. Right now, my Cavaliers are getting torn to shreads by the rhodok elite halbrediers. Why? Because those bastards unhorse them then proceede to beat the crap out of them.
In the end, to help solve this issue, all that needs to be done is to give each faction a (Weaker then rhodoks) dedicated spear line.
"I have to agree to some extent. It's the reason
I almost always use fulll cavalry. Namely Master Crusaders, Lordless Knights etc etc etc. Cause really
300 Master Crusaders cut down pretty much everything I've come against so far with very VERY little issue"
BTW, if you are using a bunch of master crusaders.... YOU ARE SUPPOSED TO WIN YOU GIT! Your argument is invalid because you are spamming top tier units
(Might I add this is why I slap people who whine about the game being to easy, yet they don't start out new each time, they just import their character? Of course its to easy! You are level 33 when you start out with 90,000 denars
)