Thats true. But if it is possible then it could be good thing to make rider to fall from his horse when the horse will stop in this manner.
I agree, there are many good things that could be done to enchance gameplay and immersion, like falling off horses, grappling in close combat(1 handers would have some advantage here
), disarming your opponents, or even simple things that were done in other mods(check vikingr;), like crouching, taunting and shield bashing, it's just hard, time cosuming, or in some cases impossible to implement them all.