In the timespan of 2 seconds you an successfully aim these moves? You lose DPS if you are spending more time then that on attack moves that need aiming and when it comes to distance altering moves, those are used in extreme situations where you need to get somewhere fast. Let's say it's T5, snake portion, your tank is having a brainfart moment and you've had to DPS far out away from the neurolinks, Twin drops after the second divebomb phase and you've just killed the last snake, you can save your healer a rez by using Shukuchi to make it to the neurolink instead of running and either wasting TP using sprint or not making it at all and dying. That is a situation specifically for Shukuchi.