I enjoy writing them.
I castled up vs Tyranids in the last tournament I played in, and nearly tabled them, but I prefer games where I get to move about. Also, Farsight is bad at castling, since he lacks Kroot. I only really had one defensive layer, and that will last 1 Turn at most. With the Trygon putting a tunnel down so near my firebase, it made sense to move away, since it cost me nothing, and it gained me room to maneuver.