Agree, the dungeon has turned from troll-friendly to leech-friendly.
The slow quest marker refresh is a huge problem in the new version (I began keeping an eye on the map to see if the pattern of movement signalled there was a boss).
The ‘logical’ solution not to miss a boss is now to leech 100%. But at least those boss room leechers aren’t gumming up the rest of the dungeon blocking minion spawns so it’s not all bad.
The worst situation is now, if a guild or organised group wants to block the entire dungeon, they can, and hold it hostage blocking all the enemies from spawning until other players give up and leave. So yes, it’s still prone to abuse, just not in the same way as before.
As well as everything @HorusKane suggested, another solution:
The bosses could speak a line in chat when they spawn, and with the short delay until they become vulnerable, that would be enough for the clearers to realise there’s a boss, and TP back.