My experience is that combat feels pretty good. I think not hitting enemies/having issues hitting enemies while mounted is more a case of not using the correct weapons/approach to deal with the target. What I'm about to write isn't meant to say "Get gud" or "You're doing it wrong". I'm merely adding my thoughts on this.
Bumping and swinging into infantry doesn't really work either because bumps typically knock infantry all the way down even at low speeds. There isn't really a mini bump like in Warband. Also, you might sometimes slide infantry away from you with your horse. I don't know if its an intended mechanic, but infantry and horses can slowly push other agents out of the way and slide them across the ground.
To me, it sounds pretty reasonable that having a horse smashing into you would no doubt nock you of your feet, considering the difference in weight of a human body and a full grown horse. In my mind, the mini bump in warband felt much less reasonable than what we see in Bannerlord. The ragdolling is why you'd want to couch a long lance/spear while charging your target head on, scewering your target before the horse crashes into it, pushing your target to the ground. While using other weapons like swords and axes, you'd want to ride up alongside the target, swiping at it while passing by. Naturally, you'll want to use as long of a blade/axe as possible, since you're mounted on a horse. Some swords (especially the twohanders) have over 100 lenght, more than enough to cut down enemies on foot.
As for getting killed if stuck in infantry-blobs while being on horseback, I don't understand why that's a cause for complaint; You're basically a sitting duck placed upon a meaty pedestal, surrounded by enemy soldiers who can come at you and your horse from every direction. Because of the danger of getting stunlocked if surrounded in Bannerlord, I think employing chock-cavalry tactics is more beneficial than melee cav tactics,meaning instead of charging in and remaining there, you cycle-charge the enemy. Instead of going for the center-rmass of the enemy force, you try to hit targets at the enemy flanks and rear, allowing you to more safely chipping of exposed soldiers.
Edit: I'm not saying the mechanics are perfect, but overall I think they work.
