Balance and single player, let me think... Do I care about how easy it would be if I had all defense boosting rings? Nope, not at all. In fact, that's kind of the point.
Modders will fix this bug, I hope. No way I will ever think of this as a feature or a design point. No, it's gotta be a bug. While they're at it, though, I do hope they add even more ring slots. And bracelet slots.