The Burn is one of, if not the, biggest question I have right now as it pertains to primals, though. Solus saw it and came to the conclusion it was created as a consequence of primals... how? Why? I can accept that their aether returns to the land once they're vanquished, but if that's true there's no real negative impact to their presence beyond warping the aetherial flow to one that favors them (i.e. the Sagolii Desert, which tips toward Fire as a consequence of Ifrit's presence).

Vanquishing a primal returns its aether to the land; why, then, the hatred for them (beyond the danger they pose to mortal life and freedom)?