If MapleStory1 was 2d and MapleStory2 is 3d

First of all MS1 isn't a failure. Despite the very low population it's still there flagship game and still making them the most money. Keep in mind KMS isn't the same thing as GMS. The population in KMS is a lot more than GMS has.  The amount of content in the game already in it's alpha/close beta state is already beaten MS1 content. The different modes of pvp, full user customization, housing system, etc is already better than what MS1 has right now. Can you imagine what kind of content MS2 is going have after it's officially released? The game is going be enormous.