I think that is the point of this. Pretty much every BLM mob is going to be as dangerous as they are in Dynamis. These are big changes. They are increasing the danger from mages because they have generally been docile for the last 3+ years.
WHM with bar spells, shell, and Sacrosanctity is going to become pretty important against terrible things.
If Rampart's duration was increased, PLD would be a much more attractive choice to toughen up your front line's defense. Would do nothing for everyone else's magical defense, but at least you'd get physical defense.
They are really trying to stop the proliferation of physical DD while increasing the potency of mages. It's like they were tired of magic not really being a part of their game. Hopefully there will be adjustments to SC M.Acc so we can see if people will stop zerging everything.
