Make all Boss Mode Boxes openable without keys. There's literally no point in Boss Mode Chests to require a key to open anymore. The chests sell for nothing. No one will ever profit from farming them. Remove requiring a Chest Key to open Boss Chests if you're not going to change the BM Chest resell price back to normal or can't come up with a better solution that doesn't heavily affect normal players.
They at least need to make the keys cheaper. Spent over 160k Carats just to get Geum SE and RE stuff. It'd be a whole lot better if they gave us a reason to open Boss Chests when we could just farm medals. Something like a boss themed rare scroll, perm exo, and perm clothes or something.