1. No, really, it's more powerful than studded leather because it stacks with monk or barbarian or sorcerer armor bonuses, as you already know.
2. This proves my point exactly. The fighter compromised his damage to get better AC by carrying a one-hander and a shield instead of a greatsword, and the barbarian negates his advantage with an unbalanced magic item.
Would like to point out a fighter who takes defensive style as one of his two styles would get a +1 AC on top of Plate, so they could be wielding a 2H weapon and rocking 19 AC. Shield would give them 21. The idea is that a maxed out w/ Bracers Barbarian / Monk is sitting at 23 AC (20 Dex + 20 Con/Wis + 3 BoD), while a fighter has the option of getting magic armor that also helps their AC and doesn't (currently) require attunement.
As for required; level 7 party going strong with no magical items having gone through ToD so far. So far, don't seem to need any magical items.