I see no other way around this if SE is to retake control over the dungeons they've created. The speedrun mentality is, for lack of a better metaphor, a cancer that is plaguing the game. Even mid-level dungeons aren't safe from people who think they're going for some kind of world record.

The following caps just might be what the game needs:

*Amdapor Keep|Wanderer's Palace (iLv 65)
*Pharos Sirius | Copperbell Mines HM | Haukke Manor HM (iLv 75)
*Lost City of Amdapor | Brayflox's Longstop HM | Halatali HM (iLv 85)

I'd see something like this as an intervention that a lot of players abusing the dungeon system need in order to preserve the game's integrity.