Is simple dude..Koreans dont want f2p to farm as much as the p2w players....that's why the nerfes are only on low/mid farmin spots.All top spots are untached or even buffed.
About the mana use...Koreans trying to remove all the mana gain/return skills....in the Archer patch they are taking away from the HE the b2m skill.Forcing ppl to buy orfen or focus on mana usage.
Also Koreans trying to simulate more ppl to spend money or go to internet caffes that they acumulate the PC point and use in the game(as u know with PC points in Korea u can buy alll kind of scrolls/pots also with the same PC points u can go to the Aligator island)
Also they have a lot of cash back systems implemented in their cash shop...so they have same price as we do but they get like 30-50% cash back+ if they were playing from the pc clubs they get more back.
SO at the end we are the region with the most expensive Ncoins/Lcoins
Even EU/RU servers have way better systems then we do.....