Yeah, Your point aside, The option is never ever to Nerf something hard-core everywhere.
If this does apply both ways, THF just became more useless outside Abyssea. cause now SA and TA will likely see severe damage nerfs, so THF's, who already did rather mediocre damage outside abyssea without the help of a Relic/Emp, Will now do even worse numbers on anything meaningful.
You remember back in the day when it was "Touch the mob, go sit in corner?" its cause THF's damage was terrible, Nerfing their biggest DD aspect (SA-WS, TA-WS) is probably an un-thought-out side effect of SE's "Cure the disease by killing the patience" mentality when it comes to small things like this.
....
However, If it doesn't effect Mobs, Or the effect is really small, My entire rant doesn't hold water. So i'll wait til the update rolls around to see just how badly it effects us all. For all we know every ~10vit could gain 1%PDT on Critical hits... Then what... yah D: