Maybe Hyoton doesn't really need a total rework, just change Bind into a more useful effect and actually have encounters that need some form of crowd control. They could do something like so:
1. Change bind so that it doesn't get removed upon receiving damage and actually have adds be affected by them.
2. Change bind into heavy/stun/silence, which have seen some use in older encounters, so it's not unthinkable that it'll come up in future content.

If they do make the CC useful, the potency would actually need to be increased a bit to similar levels of fuma/raiton since ninjutsu is such a big part of NIN dps. Otherwise the CC job will just go to the BRD/MCH since they have role skills for it and thus incur minimal DPS loss (or no DPS loss if it doesn't affect their rotation), and even if it's useful, Hyoton won't get any use.