Thinking about it, the best change would be slashing horse HP by a third and set armour of all unarmoured horses to something minimal... say, 5. Then make more open maps, random plains and such, less town circle running nonsense and less maps where you can ride to their spawn in 10s and couch someone for lols.
The benefit is twofold, battles looking like actual battles, and ranged countering cavalry reasonably effectively while having their effectiveness vs infantry unchanged.
If anyone is worried about ranged cavalry countering normal cavalry too well with it, you could make HA skill be every 9 agi. Debatable if it would be needed. And give old lance radius on spears, please
Bump damage is fine, people jumping into horse's face before bump damage nerfs to avoid being hit was retarded.