It technically IS utility. As it can be something to help u skip mechanics etc. (if it were done right, which is the main issue, it ended up not really being done correctly)
But its also not the "utility" that most people mean when they say "Utility". Which is the next issue. People usually mean utility in a different way, which is a bit vague, and has a lot of exceptions.
It's a DPS loss, because, from the creators perspective, if it werent, ppl would be trying to keep TBN on CD as much as possible, so as to keep spamming BS, and if so, that would effect its usefulness if its on CD when a tank buster is going off. (Similar to how plunge might be on CD, as a DRK wants to use it for DPS< but then gets knocked back, unable to stop themselves from falling off an edge.)
(But yeah, MP holds a greater value than Blood in most cases, with exceptions. Thats one of the reasons why you want to use delirium with Blood Weapon, instead of BS
Bolded the part about hitting everyone, as thats the key bonus for PLD.
IB being a GCD, and more of a DPS loss than TBN, since TBN tries to almost refund the DPS with blood. Plus the real issue is that IB doesnt target a party member.
But dont get me wrong, I agree with the usefulness of IB as well. Its amazing. I would consider a WAR for a MT over DRK, in HW, solely for inner beast, oGCD stance dancing, storms eye/path, and holmgang. As those abilities can make ur life as a healer far easier, and give some slashing dmg in case u didnt have a NIN (now SAM too)
Personally rethinking some things, I think TBN needs to becomes at least 15% mitigation for allies, to (1) make sure its actually making a difference, (2) make it harder to break the shield, (3) and to then make it fair for a DPS increase to keep TBN on CD. DRK almost has enough CDs for tank busters w/o it, so honestly a DRK can simply learn to just not use it for 15s, if they know a TB is about to pop in less time.
If BS actually becomes worth while, or TBN grants more blood, or even the MP of a syphon strike, that also would put it into a DPS increase. This would raise the skill level of DRK too.
It would be seen as a major raid utility job, but it would still be good enough.