When we complained about the economy before 2.1, they said "hey guys, PvP gear and furniture is coming!". Of course, a lot of people don't even bother getting the crafted PvP gear, and since nothing in it is particularly rare, everyone can make it easily and it was a quick race to the bottom in price. With furniture, since almost no one can even buy a house (I think there's only like 1 house on my whole server... lol), the supply for furniture is just about light years above demand, so expect prices on that stuff to always be pretty much rock bottom.
ATP items have dropped in price constantly since release, the rate of which was greatly increased with 2.1 since now it's even easier to get ATP items (like potash, coke, etc.).
Does no one at SE realize that if nothing is rare, nothing is going to be worth anything? It remains that the only thing of any particular value is high grade materia, and even that has taken a bit of a hit thanks to quests handing it out like candy. Though I do think it's kind of hilarious that the best way to make money is to run around in dungeons wearing trash gear, which is so counter-intuitive to how one would normally play a game it makes my heart hurt.
Anyway, would it be so hard to make some valuable items that aren't easily obtainable by everyone in the entire game? Making all the high level crafted items use ATP items as their "rare" ingredient does nothing to make them valuable, since everyone on earth can get ATP items very, very easily. In FFXI, you needed things like venomous claws to make scorpion harnesses. Stuff that only dropped off certain NMs or BCNMs. There were a lot of other rare ingredients that only came off of certain monsters that rarely spawned, etc.
It would be really nice if this game had high level raid fights against things that dropped rare crafted ingredients, that could actually have value so you could sell them for a worthwhile sum. Instead, everything is so common that it's an immediate and constant race to the bottom on price, to where everything loses value almost instantly.
It would be great if the game more easily allowed you to accumulate gil, and put in more gil sinks as well, rather than hoping people will blow hundreds of millions out of the economy for stuff like houses. Need more subtle gil sinks, not things where you're like "hey the economy is crazy, nothing is worth anything, yet their is insane amounts of gil in the hands of a few, so let's try to make them pay 300m for some houses". Maybe look more at the WoW economy, or even FFXI's, or really any game besides this one. Of course the economy is going to be terrible if nothing is of value so gil rarely trades hands in large amounts. You can't just rely on materia alone to drive everything. There needs to be rare stuff that people want that not everyone has the skill to get.
Speaking of FFXI's economy, I actually think it was a huge mistake to give crafters stealth. Part of why anything was valuable that you mined in FFXI was because it was in dangerous high level areas where you'd probably get killed while trying to mine. Unless there is an element of risk involved, preferably also involving a skill check, that stuff isn't going to have real value. In fact, people will just bot it up and flood the market. It doesn't matter if stuff only pops once a game day. That isn't going to do a damn thing to limit supply in any way that means anything, because supply will still overtake demand by an incredible margin.