This is not a rhetorical question:
Why do you the loot developers keep forcing AC on cloth-wearing casters, among other illogical things? On my sorcerer, my defense says exactly 5% miss chance no matter which AC item I wear (or the number of them), and nothing in respectively leveled content is going to be hitting me for less than that AC can successfully block.
The new dragonscale robes all have AC, but on top of that, you can upgrade them for more AC. Useless!
Fortification, or some kind of damage reduction/mitigation would be much more useful and make sense.
Better yet, add slots and let us decide