IMO, the tank dps nerf was less about "tanks do as much damage as dps" and was most likely more about trying to force a paradigm shift in both the tank meta and the way the roles interact in a party/raid environment.
While a good tank could do approximately as good damage as a not so good dps, skilled dps easily did a good amount more damage than a skilled tank. Whether the difference was enough is somewhat debateable. However, this does lead to the controversial topic of how many dps (not all of course) have been playing suboptimally and have been able to get carried through content by the other roles. This is the "way roles interact" part that I was getting at, that by lessening tank damage it puts more responsibility on dps to perform to compensate for that loss.
Now for the "tank meta" I am talking about the highly aggressive, "STR tank", dps stance tanking meta that has been a thing in this game for a while now. This meta is both good and bad as it is good for those that know what they are doing but bad for those that don't and unfortunately it created a situation in which a lot of inexperienced tanks or not very good tanks would try to follow the meta and perform poorly as a tank because they never learned or were able to handle the "tanking" part. I have a feeling SqEnix was not so hot on what the current meta had lead to and so wanted to shift it back to a bit more of a defensive focus for the role, therefore putting a greater emphasis on learning and putting into action on a regular basis, the basics of tanking in this game.
So in conclusion I feel that in order to force more responsibility of group dps back onto the shoulders of the dps role as well as to force more tanks to know how to tank, SqEnix decided they needed to be a bit heavy handed and implemented the overall tank dps nerf. It is of course by no means the end of the world and dedicated tank players will continue to play it because they love the role, but yeah nobody likes getting nerfed even if the reasons behind it were potentially sound.
As for people not being rude and childish in their responses, I agree and people really need to start putting the "common" back in " common courtesy" because these days it seems like people are considerably more ready to spit poison and fling feces at each other than have any civil discourse.
P.S. I do feel the nerf amount was a bit much as it is right now, but I am curious as to how it will scale with the equipment since VIT based gear tends to give a bit more VIT than STR gear gave STR. Will the greater VIT per gear piece end up adding up enough that the current nerf gets noticeably lessened? Who knows and it may be hard to tell now or even in the future but it is something that may warrant consideration.