The main problem is the event prices, that drives the game i know, but a lot of players quit or move to other servers because of it, it also needs an improvement to make it worth paying the fee as Draeke pointed out.
The drop problem that everyone talks about, it's a game feature, good drops in end game instances that get nerfed as the population reaches there, it's the game design, blame the Koreans... Anyway, before complaints, you should really read and learn how the updates are going over in Korea, nerf stick and booming prices are coming, stay ahead mate.