The ability to move with your main castle is limited, as it was misused to "jump" and thus attack other players unexpectedly. Because of this, it is now only possible to move your main castle if you are capitulated.
There are also other reasons for wanting to move with your main castle, than attacking an opponent. Reasons that may give you more fun in the game: Wanting to get away from a hostile or crowded environment, where you can't grow. Sit closer to friends, so you're safer.
My suggestion: A player who would like to move, gives the player name and new coordinates here in the forum in a special topic. If no valid reason is given by other players, the main castle can be moved after 14 days. After the move the account can not attack or be attacked for another 14 days ( 14 days capitulated without the extra bonuses).