Well to add to the topic, I never was able to smash an army like some people could in MTW with 1 jedi general. But in RTW I can defeat a whole army with 1 family member. Sure they should be a strong unit but not cakewalk everysingle unit in an army.

Part of the problem is fatigue/killrate, most battles are over with most units saying warmed up. In MTW a cavalry unit might be able cakewalk a few units but after the second are 3rd unit they'd be fatigued enough that they needed support to be of further use. Cavalry and support !!

Now I do love some of the ways the new fatigue system works, such as all units can get back to being fresh status wich was actually more of a needed feature in MTW than RTW due to the reenforcement mechanics. I could live with desert fatigue but nothing as drastic as MTW. It's also nice that cavlry can recover fatigue while marching but infantry should also be able to do the same or at least get back to winded or warmed up while marching

Overall though I'd say it's more to do with killrate than fatigue. The other problem is that cavalry moves so fast that it can move to hit the flank of infantry. You can see it coming and the infantry have no chance of facing the threat. You are better of letting the infantry stand still and take the hit in the flank than have them facing the cavalry but moving.

Cavalry was usually pretty poor when attacking (prepared) stationary infantry, this is in consideration that the infantry is professional.

Cavalry's biggest power was thier mobility, not the power of thier charge. They could fallback when the losses weren't acceptable and they could rush to exploit an enemies weakness or rush in to a weak spot of your own.

Also thiers a reason why cavalry was almost always deployed on the flanks, mainly due to thier mobility. Think about when the A.I. charges your skirmishers in the center. Thier cavalry gets mobbed because there is just to much support there or just from the natural pushback they cause they are quicly surrounded on 3 sides.