It has become a runaway train. People cry for more adena slots, but what needs to happen is the reverse. First, they need to cap total adena that any account can have. If that means wiping out excess adena on accounts, so be it. Secondly, they need to roll back the NC base price for all items and make it impossible for players to charge more than 5% premium of actual base cost. Third, totally revamp the NPC stores to sell every item in game and upgrade the Luxury Shop to include a normal Night Market exchange, albeit at reduced prices.
Let's face it: the market is the most toxic aspect of this game. Fixing that will make the game competitive, because everyone will be able to get what they need from an NPC, as opposed to just a handful of players who control and ruin everything.