I'm a (very) amateur player and have seen the use of en-passant only a couple of times in club games. Chess books I've read (Soltis, Weeramantry, Pandolfini,etc.) feature hardly any games having ...
Other than castling, the only "strange" move that chess pieces can ever make is en passant. It seems a little odd to me that someone thought that such a "different" move was so important to include ...