Proposed use for primal weapons.

[Milkskates]

Progression always obsoletes older gear. You always replaced previous raid gear with newer gear in WoW, and that seems to be the model here. FFXIV follows FFXI in making Relic weapons a little more significant, so that Relic + is the best weapon gear, but this doesn't hold true for armor at the slightest: You start replacing AF gear with Darklight almost right out of the 50 gate.

Old gear can be used to reskin new gear in WoW though.