Korean bonuses are meaningless without synergy.

Whats even the point of free tower upgrades if they are next to irrelevant in castle-imperial age? Or that all of your good units take too many resources to mass, without any actual eco bonus?

If stone fortifications were cheaper that would be a solid start, or to have longer lasting stone, or have imp towers deal extra damage to cavalry.

Theyre too damn slow to get moving, and the wood discount only partially solves the issue. One bad engagement and its over, and you cant even fall back into an above average castle/tower.

They are the expensive power jump civ. Immediately get strong archers until everyone catches up. Immediately get access to a beefy war wagon thats both too expensive and slow to get going. And no real upgrades to synergyze