1. New Settlements
2. Daily activities, mini events that occur once every Mabinogi day and give a shot at good rewards. A unique daily would exist in each settlement.
3. More frequent field bosses.
4. Caravan minigame. A group of NPCs need help running a convoy between two settlements, protect the caravan from bandits and wildlife to receive a prize.
5. Update rafting. Players currently raft solo because the star count is shared between players. If that mechanism was removed you might actually find rafting parties.
6. New dungeons.
A couple of ideas.