When the servers can't handle the quest, it's poor design. You have system limitations that can't be ignored during design just because you feel like it. There is a reason we don't have standard dungeons with 40+ players that spawn multiple waves of 10 mobs at a time in 8 distinct map areas at once with an autofail condition worked into the quest and a 2 hour timer between repeats as well as an "overflow" instance that typically has so few players it's autofail for those not lucky enough to click on the door fast enough to enter. It doesn't take a dev to realize that's a recipe for disaster.
I'll admit, under good conditions, when the event runs smoothly, it's a nice dungeon, but it's clear that these ideal conditions do not exist in a typical instance of this event. It needs to be shelved until the dragon chamber is reworked to run within the limitations of the system.