Mounts are too rare
I have played through multiple full games without ever seeing a resource node for horses or wargs, or seeing them available for trade from other factions. I think that they should be somewhat rare; it would be wrong to be swimming in mounts and able to make every single unit mounted. But it's frustrating to go an entire game without finding them anywhere on the map. Maybe one of the orange "find new resources" techs could guarantee that 1 faction-appropriate mount resource node show up in or near your territory?