If it is blowing offshore and you are going out over a stretch of shallows, hoisting the kite enables you to sail out instead of walking the boat out. It also impress your competitors a lot when you zip past them at 15knots, rudderless.
The same can be done when going in, but its harder to find the right balance between sailtrim and crew weight.

Practice in an open area before trying it close to shore/obstacles/navigational hazards! It is easiest to get going on a reach. Learning to control your boat without rudders give a new feel for the boat, and is a good way to become faster on the racecourse. Johns post sums it up very well.