Okay, I’m functioning on less than 2 hours sleep within the last 48 hours, so these might or might not make sense:
Remove most gear as quest rewards except a few quests
That level 5 check you get early on? You need to buy from either market or NPC at least two slots, though it’ll likely be all except the custom-made body slot.
Less productivity when crafting
Everyone can craft a dozen HQ rings in half an hour. That’s a lot of rings entering the market. How about lowering the HQ percentage and also making crafting a bit more time-consuming (Quick Synth should take thrice as long for the amount of stuff you get if you, for example, craft 99 leathers). This slows down the influx of items.
Lots of special crafting stuff can be found in dungeons
Such as ingredients and gear (alternatives to Luminaries found in CT/Coil?). These can then be sold by raiders/battle lovers (or they might be able to commission what they want), thus giving them an income from crafters.
There are BiS craftable gear
This shouldn’t even be up for discussion. If a hardcore anti-crafter wants BiS, he can either commission a crafter to make it for him, or buy it from the market.
Extensive commission system
The commissioner puts up a notice near the market board and gets a few answers. They can see the iLevel and rate of success and HQ when picking the crafter they want, and submit materials and gil. The crafter then crafts the item and submits it, getting their gil. Sometimes, NPCs wants very expensive commissions that’s like hitting the jackpot for crafters.
FC Housing needs a bit of an overhaul
Plot price for largest and best location should never go above 100 million (50mil for large land plot, 50mil for location. Smallest plot/worst location would be around 1mil). Then crafters and gatherers are needed (or you’ll hire a substantially more expensive NPC) to build the house.
This is the craft/gatherer equivalent of Coil/XM Primals as each floor of a large house needs at least 10 000 raw wood, for example, that then needs to be crafted into useable wood by carpenters (and alloys need to be made by ARM/BSM which are then turned into proper nails/hinges/whatever by GSM). Crafters then need to spend a certain time at the plot building it (or hiring an expensive NPC).
Afterwards, once a month, there is a bill of 100 000 (if largest/best location) and a 100 (not dependant on location, but on house size) of each material is needed for upkeep (can also hire steward/maid/butler/FC retainer who automatically use the funds/materials given to them to keep up the house/bill payments. Of course, they also needs to be paid).
Potions need their own, separate cool-downs, and reduce it by 25%
Just to make alchemist a bit more attractive.
Elemental strengths and weaknesses
Just to diversify things and keep the money flowing; for example, you cannot beat XM Ifrit without fire-resistant gear and ice-attributed (through either materia or special weapons) weapon without a lot of difficulty. This means that more gear will be bought and sold.
Boost Leve money rewards
About twice as much would be good, since we need a lot of fountains to go with the gil drains. (Also, boost the allowances a bit.)
Daily Gathering contests
Once a day, gathering guilds call their gatherers task; Miners/Botanists compete on who can gather the most NQ/HQ (separate categories such as Most NQ and Most HQ and Most Overall) and turn for great rewards, as well as Fishers try to snag the best fish they can find (size, quality, type of fish are different categories with different levels of rewards, so the largest HQ Princess Trout might only get 100 gil, but largest HQ 1-5 level fish might get 1000 gil, while levels 1-15 gets 2500 gil, and 1-30 gets 5000 gil and levels 1-50 gets 10 000 gil).
Personal housing stuff
A lot like FC housing, only a lot cheaper; smallest on worst plot is 100 000 gil, while largest and best plot is 10mil. Subject to same bills and taxation and so on.
Bounty hunting
What it says on the tin; at the Adventurers’ Guild, there sometimes pops up new NPCs who want you to hunt down a boss-level monster for them. If you help a farmer/miner/fisher, you get meager gil reward but a week’s boost to gathering (gathering HQ materials). If you help a Yellowjacket, you get a reduction in Limsa Lominsa market taxes and so on. Is recommended to do in parties, but has a few solo-bosses and a few solo-with-NPC-party.
Have a really good Vanity system
Crafters can learn patterns by picking apart uncraftable items (destroying them, unless it’s a one-off item, in which case there is a quest in the corresponding guilds that teaches the patterns when crafting level and gear’s class level reaches 50) which they then can freely apply to any piece of gear. Likewise, dyeing is unrestricted.