I actually like the assisted movement, makes it more realistic i think. Have you ever actually ridden a horse? You point them in a direction, they'll follow that trail or road, but pick their own path down it. Maybe there was a snake or something between those trees?
There's a spot near Lucky's Cabin that my horse would not go to at all, where the floorboard or fallen fence or whatever it is, is lying by the small tree. Horse threw me when i tried to go there. Went there on foot and i could hear snake sounds, but i couldn't see any snakes anywhere around, even with deadeye on. Glitched out snake maybe?
I really like the "upgrades" to the horses from what was in RDR. Like that you can calm them down now, when a predator comes near, or a gun fight happens.
Agreed with other's the tree limb flinging you off the horse at high speed when you're walking by or trotting by, or trotting into a boulder and ending up airborne for 50 ft is a bit extreme.