Jeff Carlsen
Adventurer
If they deliberately design an item to stack with other AC boosting items, they can put that in the item's rules. There can always be exceptions to general rules. Right now, the general rule is that AC bonuses all stack and an item must specifically state that it doesn't stack, as with the ring of protection. I just want to reverse that, and have the general rule be that they don't stack unless the item specifically says otherwise. No "design space" would be closed off by doing that.
I'm not sure if I agree or disagree. What I do care about is that the armor bonus be defined in the story. One thing that third edition did well with it's keywords is to give a sense of what the magic bonus is doing for you. A deflection bonus is a force field. An enhancement bonus makes your armor stronger. Preventing abuse matters, but I also want effects that would sensibly stack to stack.