To be more precise, what's the reason for the lack of high quality 2D sidescroller MMORPGs? Only ones that I know of are Maplestory and Elsword, Maplestory being too old and Elsword being, well, not exactly 2D.
When I think about it, it makes a lot more sense to go for a 2D sidescroller MMORPG than going for a generic 3D MMORPG which is pretty common these days. There's also the fact that it's pretty hard to compete against games like "GW2, FFXIV, Black Desert,etc.". Is my thinking shallow here? Is there any reason for game developers to not to choose this type of MMORPGs?