H. G. Muller wrote on Thu, Jul 17, 2008 09:50 PM UTC:
Well, as I explained, I cannot imagine who would ever want to use other King destinations than those to b- of g-file. Adding moves that are not attractive to use, will hardly lead to more variation in play. You can make variants where it is allowed to remove your own pieces from the board, in stead of moving them, or cpture own pieces, or teleport your King to e4 in stead of castling, but it will essentially stay the same game, as no serious player would ever consider it.
I have a strong suspicion that this castling rule flls in the same class: strong players would virtually never use the extra possibilities.