Promethium is already in-game (obviously donator exclusive as well) and still leaves a tier of BIS gear unreachable then. Whilst there was never an option in the past for those who donated for them to have the potential of grinding, Primals have been in-game long enough for those who spent the money to take full advantage of them (use, sell, hoard etc).
If an item isn't obtainable in-game and is exclusively locked behind a paywall, Ely becomes a complete P2W server. As the options offer; if you want to donate for them and save a grind, go ahead. But if you don't fancy spending $50 or however much they are, you still have the option to pay.
I am in full support of Primals being added in-game; gives an actual incentive for Dungeoneering to be reworked to fix this, opens up more gear possibilities for those looking to expand, gives players another thing to grind for instead of afking at home and can also add a new section for Collection Log hunters to further increase longevity.