the answer is quite simple. i have said this before and it is still true. Maple has the better quest system. RO have better skills, classes, game play, and a better economy, but they skimped on the quests. Maple has several times the quests RO does, they are easier to find, and range in both complexity and the player skills necessary to complete them. RO you have to do a Wiki search just to find out there are quests, and they are all dozens of steps in length. Further, later patches broke some of the quests, without changing them ( the assassins guild quest in particular). It was a mistake and it cost them.
However, the private servers can make up for Kro's opps. Everyone, script quests now!!!