3D boards may sound cool if you've never tried to play on one, but for some reason its harder to see everything and therefore harder to follow the game. So in a word, ewwww.
I think a 3D chess simulation would make it more realistic. After all, in a real game, the board isn't 2D. Maybe Erik could make it an option if it's ever actually implemented. (I know how much other stuff he has to do.) It would just be another style of chess board that you could choose from the list.
The 4th dimension is roughly considere to be time. So we already play chess in 4D. Add that to the 2D boards on this site and divide by two and behold' we are playing 3D chess. Mwahaha
It's better to make the board 3D instead of 2D.It will be more fun.