I only had it done when I installed my lift/tires and balljoints to make sure all my camber/toe was on point. Im sure I could have done it myself, but it was just a time saver.
Unlike the TJ before, your toe will NEVER change on a JK unless you bend the tie-rod. Unless you install adjustable ball joints, your camber will not change unless you have a bent end forging or axle tube. There is NOTHING that an alignment shop can do about this. Neither of these thing are things you even need to do yourself UNLESS one of the before mentioned has occurred.