Can I please ditto this? As it currently works, World Bosses during events don't stay standing very long. That pretty much is as it is and I don't see anything which can be done to change that, so you either get in your licks quickly (and hope for loot) or wait on the respawn and try again. It's the side-objectives which are problematic. Perhaps take a cue from how they were handled with later expansions where WB side-objectives are instanced for each player? In the case of the prisoners on this daily, they spawn along with the mobs from whom we're supposed to rescue them, so the problem is more their being coupled with respawning mobs than it is a problem with the side-objectives. Maybe make the objective to rescue all four and run around and untie them (they are definitely not proximate to each other) instead of needing to wait on the mob respawn timer?

In a nutshell, a mechanic which works fine during regular play becomes a problem when there are a lot of players all trying to do the same thing at the same time and the thing is one-shot on a timer.