The source of those crafted items are one of the few things actually pulling gil out of the economy.
You could still pull gil out of the economy by just allowing all players to buy the AF+3 crafted items from an NPC, instead of from a crafter who synths the NPC-able ingredients. And you could set the price for something like a Ruthenium Ingot lower than the ~4.7-5mil AH prices (which never dropped in line with a natural drop in demand over time, due to the price of the needed materials for crafters to make one).
At this point there is very little logic for why AF+3 items should cost 5-6mil, when:
* Most Relic+3 cost a fraction of that if you buy all materials. And the relic upgrade items have multiple acquisition methods, from buying on AH (like craft AF+3 mats), to farming the shards/voids in Dyna, or obtaining through AMAN Trove. Hell, give us some alternatives for the AF stuff too - make the pricey AF+3 upgrade items drop from Limbus bosses or be purchasable with some new Limbus currency (Limbus Accolades? lol)
* Empy+3 requires no gil at all, and also gets easier over time to earn the Galli as people learn Sortie or improve their other gear.
* Odyssey gear (e.g., Sakpata set) is another gil sink, and is also a lot cheaper than AF+3s for what are comparatively much better pieces in most cases. Also became cheaper over time BY DESIGN, by decreasing the server price as more people bought the gear and paid that "FIRST" tax.
So why does AF gear have to be the untouchable set where we just can't adjust the biggest roadblock of prices that never decrease and are generally out of touch with the utility of the items? It's not just due to needing a gil sink (which has done very little to impact the overall in-game economy in years, since it's not exactly like there's a massive demand for these items any more), and they could still create a gil sink by just adjusting item acquisition (NPC sale of the +3 items). Hell, you might even remove more overall gil from the economy if they made the pieces cheaper to get. I'm a completionist and made every AF+2 piece for all of my jobs, made some AF+3, but I'd make even more just for the sake of saying I did it, if each piece was less costly.
Perhaps "AF+4" is gonna be so good that people will suffer through the annoying step to make the +3 piece needed and just view that as one part of the total AF+4 cost. But IDK, it just doesn't feel in line with the progression we've seen with other stuff, like the aforementioned multiple paths to upgrade original AF/Relic/Empy to the ilevel reforged versions. IIRC, fairly recent dev comments also talked about wanting to streamline the process to get gear up to current max level for players starting it from scratch. Revisiting AF reforge upgrade requirements would align with that kind of thinking (as does stuff like this update's reduction in the cost of ambuscade armor/weapon upgrade items, which may well be setting up for stuff like +3 armor and beyond at some future point).
As it is now, the AF+3 requirements are only really providing a minor benefit to crafters who make a small profit on the completed synthed items, if they even bother to risk making stuff that doesn't sell all that fast. Kind of annoying that the AH might just be sold out of the item you need, especially on lower population servers.