This is important to note.

Surecast doesn't work on most unavoidable mechanics. This is because those mechanics are not coded to cause an interruption. Surecast is a "The thing is directly hitting me" spell and that's why its worthless.

The mechanics it lets you cast through involve you not moving out of them or taking a boss punch to the face. The former is what you use swiftcast for, the latter means something else is severely wrong.

Outside of PvP (And even within it, given they give you -10 second surecast- as a pvp ability), Surecast is in that margin of usefulness where it may as well be useless, much like Sleep (outside pvp) and Freeze (...in general?)

Surecast and other Black Mage abilities need another pass at them because they do nothing for you 99% of the time. This is well beyond an acceptable range for 'niche' abilities, much like Dismantle and Rend Mind for Machinist or Repose for White Mage.