At release, Lineage2 was bigger than Lineage1, the reason lineage1 is stilla bigger game is because of accesability. In Korea/China etc where most people can barely afford a computer let alone a half decent one 2d games are far more popular.
The reason WoW has done so well over there is because its a 3D game that looks good and has exceptionally low requirements. I prefer 3D games over 2D games because there is more immersion and far more depth to the play than in most 2D games. That said if I had a choice between an exceptionall awesome 2D game and an "ok" 3D game I would play the 2D one.
The fact is most games coming out nowadays have a focus on graphics being 3D anyway and the storyline/quests/playability are just as good as, of not better than many of the older games.
the important thing is how many peoples are online after a while, not at the start, lineage 1 have many peoples around, even though its 2D, the fact that there are other free mmorpg around with 3D that don't require good computer like silkroad just shows that 3D/2D is not that big difference, the thing that make 2D better for me is that it usually got better story.
what i don't like about changing games from 2D to 3D, is that if i liked a game at the 2D version, i want it to continue the story with about the same system, i want the game to look about the same, so it will be really the sequel of the game, and not some other game.
2D games got better story because they focus on the story when they make the game, not on the graphic, when companies make 3D game they focus on uber graphic and the story is kinda go around the graphic. 3D developers are using the fact that you will most likely put ur attention on the great graphics and not on the story.