The Vault Block: Better Items & More Locations.

The vault block is a great solution to sharing loot between players on multiplayer servers. With the items currently present, it gives really good loot if found early game, and decent loot at the middle of progression. Besides encountering the new Breeze mob or possibly creating a form of mob farm with the new Trial Chambers, late game players have very little reason to seek these rewards out, pending any information not released yet of course.

With a tweak to the spawning locations and the reward mechanics, I think it'd be very easy to make vaults more enticing at every stage of the game. First of all, I think there should be at least one vault at the Desert & Jungle Temples, Stronghold, Nether Fortress, Woodland Mansion, Ancient City & Ocean Monument locations. The new Vaults at these locations should have a slightly higher chance at rolling the unique loot found at those locations, making the player really think about the kind of reward they're looking for.

Secondly, I think The Vault blocks found in the trial chambers themselves should have a tiered reward system. Using a similar method that the trial spawners use to visually indicate what mobs will spawn, the Vault block could be surrounded by three different materials to indicate which reward tier it belongs to. I'd use Wood, Stone, and Obsidian blocks. Harder blocks mean higher tiers, higher tiers mean better rewards. Higher tiers should need more keys, which should also be customizable via datapacks/commands.