Unfortunately, this fabled newest interview is the only time they've responded to Dark Knight issues directly since Stormblood started (and perhaps reaching far earlier).

What I took from it was that they notice party composition and usage statistics in deciding balancing factors in jobs, that the tanks are close enough right now to not warrant alarm, and also Dark Knights are immature siblings that saw Warrior get a present for Christmas and want one too. The last part feels implied.

But I decided to focus on something I now know they notice: party composition and strategy. If there is a major decrease in party compositions including Dark Knight, they can notice and comment on it. I really don't care anymore who thinks Dark Knight is fine or not fine and in what ways, I feel something needs to be done for my enjoyment of the job and if the only way to get the message across is the aforementioned way, then so bloody be it.

(I do think Dark Knight is, in small (DPS), medium (TBN) and alarming ways (useless skills, overall mitigation) behind the other tanks, but it's past the point of convincing others now.)