Except that with cav you have double life (if heavy horse more like three lifes), ability to ride away from anything with great speed, doing unblockable crap like bump lancing/slashing, and doing awesome pierce damage. Oh yeah when you get dehorsed you're also a footman just like any other non-cav footman, just 3 stat points less.
With cav you don't increase you own HP, and you either sit on something that can be oneshot by any decent build, or sit on something that feels like a supertanker, even though you have to catch powerboats that copulated with mosquitos. Either way it's a big ass target for any non-blind archer. Also, losing your horse automatically makes you take a nap on the ground (the longest stun in the game), long enough for some people to get 3 free hits. So when you get dehorsed you are a normal footman like every other footman except that in average you took two solid hits, so most often you are a dead normal footman. Moreover, sure you can run away with great speed, but during the century you spend accelerating, you can easily get hit and ganked. Not even mentioning the fact that when a human stands in front of a stopped horse, the horse cannot push the human, it's like a brick wall. Finally, the "awesome" pierce damage was already not enough to kill some archers with full speed bonus before this patch. Now it's more like "pityful".
If you try to block a lancer, you are doing it the very wrong way. No matter the attack he's planning (btw all cav moves with any horse and any build are telegraphed 2 hours before being executed), there's always a way you can dodge and hit. Things like bump-"something" are the easiest way to get killed for a cav, cause they have 0 defense while doing it. If even with a 2h you get killed by cav in duels I really don't know what is wrong with you.
btw even if I sound mad I am not that much. I abandoned cav. It is just irritating to witness such ignorance.