Suggestions to the team regarding chest drops.

I think Chest (Armory Chest) should binds to the Stage Level or Kingdome Level.
We can debate about making the Resource chest Grindy but Armory chest should align with your level of Stage and Kingdom so that you can fight-off Monsters easily.
If You are Level-0 Kingdom and just starting off Current Drop rate is good.
When you move to Kingdom-1 you will have slight chance of getting Level-2 Gears much often. If you advanced to Kingdom-2 and Stage-2 (harder enemies) you have good chance of getting Level-3 Gears.