This design decision completely screws over casters.

If you buy the AF2 chest as a caster, you're stuck with the Amdapor helm or lower for 2 weeks until you get the AF2 helm.

Meanwhile every other damn class that's not a caster gets to mix and match pieces without getting screwed over by upgrades.

Only tanks suffer from this, and at least they get to use 2 Darklight rings while casters get stuck with 1 because they made the stats separate and the rings unique.