Old Icons

Because there's still hope that they'll eventually come out. But the old destiny icons were replaced twice and now even the destiny system is replace.

If they implemented the Lugh Persona but never released him prior to G16's end, then I seriously doubt they'll add it.

My point is, no matter how unlikely ,there's still a pico-scopic chance that it will exist. But no chance of them removing the Talent System and re-adding the Destiny System.