Shukuchi is a lot like Aetherial Manipulation is for BLMs and Elusive Jump for DRGs - you don't have to use it, but if you figure out how it makes your day better, it's fantastic.

For 4.0, I'd want NINs to focus a bit less on support and a bit more on slicing things hard and fast. Think Akatsuki from Log Horizon. I don't really have any specific things to add to that, though, and my stance on 4.0 in general is still that they need to rethink the skillsets in general and focus more on merging skills and adding more traits to combat ability bloat. As a controller player, I have no problem actually binding ~40 skills in an easy-to-access way, but at some point it just becomes un-fun to have that many abilities to track.