Like any time there's an invasion and you want to pop back in? Or meet someone in landing bank for a transaction at a moments notice? Landing is pretty much the central social point of the game. And it's quite convenient to be able to move around like that, not to mention being able to leave scatter and other annoying places. Also it's unlimited unlike those 1x/day mounts. People routinely pay far more for far less in this game, and this one isn't even the most expensive of cross realm items out there.