Doesn't matter how flexible and available something is if it has a 50% chance of hindering your gameplay or performance. The ability is cool in name only. Half the time you have no way of guessing if something will break TBN. It should just be a shield with maybe a small excog effect applied if the shield breaks, but at 25% of max HP, it's worthless, even as a shield. Scholar shields more than that by just casting Adlo, and that is before buffing it with Fey Illumination, Dissipation and Protraction. I often get more value out of Oblation than I ever see out of TBN. If not for it's value in the level 70 ultimates, TBN probably would have already been reworked. You think I don't value it's strength? No I have far more understanding of how it works and when to use it, and I still see it unexplainably fail to break sometimes. Either someone unknowingly adds in their own mit at the last second, or damage variance actually rolls low enough for it to not break by single/double digit numbers, in which case, oops, guess you were just that unlucky. Sometimes I'm waiting for enough MP and it's so close to when I need it that latency sometimes says "no, you didn't have TBN up in time." That really only happens in 70 ultimates where I'm using TBN way more often than in savage, but it's still a major flaw in the design of TBN. It may be unique, but it is definitely not good, regardless of how you look at it. The in a vacuum argument is completely irrelevant when there are plenty of examples outside of that which show the ability to be even worse than it is in a vacuum.

TLR
This isn't 2016. Heavensward dark knight is never coming back. Homogenization is the name of the game. If you aren't used to it by now, you are probably playing the wrong game. Oblation needs a regen. The Blackest Night needs to be overhauled.