Yoshi P talks about Warriors- from Producer Letter Live @ TGS

[Ruminate]

Let's not forget, defense is worthless and you're not exactly getting boatloads of it every time you upgrade gear. A few points, yay. That's not stopping me from taking more damage.

This is flat out wrong. Damage reduction gains from Defense is linear. Every point is better than the last.

Most MMOs give a linear amount of armor/defense as the item level rises, but apply diminishing returns to the mitigation gained per point. This curbs the ever increasing returns phenomenon.
In FFXIV, there is diminishing returns on the amount of defense gained as the item level rises, but the mitigation gained per point is linear.
The effect is the same in both cases, the difference is that 1 point of Defense in FFXIV is worth a helluva lot more than 1 point of Armor in other MMOs.