What they mean by "change the damage calculations of tanks"?

[Syzygian]

Str specing your tank or vit specing it has ZERO to do with your in-combat skill and ability to maximize your dps rotationally and mechanically, so no matter what they do with gear or behind-the-scenes damage calculations, maximizing your performance as a player with your job isn't going anywhere. If anything this will balance the playing field and show who is actually playing their job right.

Essentially what people are scared of amounts to seeing smaller numbers on the screen, nothing more. As long as you are maximizing your performance it doesn't matter as long as encounters are scaled to whatever tank dps winds up being (honestly probably not much lower than it is now, if at all). Players that are bad that rely on str gear to pump out decent numbers will be a thing of the past at least.