Monster digging breaks vaults
Unfortunately these vaults no longer work in D, Depths, or Vaults (which almost all of them are exclusive to), because someone thought it was a good idea to give dig to some really common monsters. Now half the time when you encounter one of these vaults, a deep troll earth mage will immediately bust it open or some monster inside will pick up a wand of digging. In old versions the chance of such a vault generating a boring beetle or appropriate shapeshifter was so low that it was acceptable (and virtually none can get a cacodemon), but deep troll earth magi are extremely common. So 5 titans get released into the open on D:12 or whatever without the player having any say in it.
Short version: Either A. deep troll earth magi need to lose dig and monsters need to stop using the wand, or B. a large number of vaults (probably 100+) have to be removed or heavily modified.