Are you saying that you don't see the difference between making a wider range of AC is useful and making not having AC lethal?
On the one side of this coin you have Armor Class (or rather Defensive minded)being a valid playstyle.
On the other you utterly cripple a different playstyle and don't actually improve the defensive nature of any playstyle.
No one actually gains anything from the change per se. They gain an illusion.
The Mid AC people say... Hey I don't get criticalled very often because my AC (with Fortification) is really high. As opposed to now in which they say they don't get criticalled at all, but they still get hit 97% of the time.
The low AC people say, I get Criticalled ALL the time because even with Fortification my AC isn't high enough to be worth a ****. As opposed to right now where they say. I get hit all the time but I don't get criticalled.
The high AC people say I get criticalled very rarely, because my AC is so high, and I only need a little fortification. Currently they say, I don't get criticalled at all.
So in what way is the proposed system, which is based on a currently non working system accomplish making Defensive Characters more viable without utterly crippling Offensive characters.
It won't even address the Rogue issue of Crit Immune mobs, because they are specifically omitted from this conversion to notn Fortification.
The Dev mentioned system gives the Devs options to have critters reduce targets Fortification in certain key battles (and likewise for players) while not crippling lower AC characters in others.
Will this dramatically help mid to high AC characters? nope... but it does have the benefit of more options and it doesn't work on the system that really isn't working well right now.
So, while I do want defensive characters to be improved, this is not the system that will do that.
Regarless of which idea is employed Fortification change will not "improve" any character defensively and really only crit and sneak attack focused characters will gain true benefit from it.
Aesop