[dev1031] Truly "Hardcore-friendly" NMs. Make us HUNT them.

[Visch]

Remove ants from the road! They keep killing my rank 17 PUG because I'm too lazy to walk around them!

Now make Vrtra fly around and kill everyone! Misdirection! Yay!

[Abriael]

True, but we would lose the effect of non-hunter passerby players of being able to tip off hunting players on where the roaming NM went ... or to join in the hunt/posse/angry mob with pitchforks.

Yes, that's pretty much it. A component of luck should not be completely excluded. Worse comes to worst, they could give a bonus to the drop rate if the group that kills the mob also engaged it's lair.

Remove ants from the road! They keep killing my rank 17 PUG because I'm too lazy to walk around them!

Now make Vrtra fly around and kill everyone! Misdirection! Yay!

The detail you're missing is that the ants effectively wandered into the entrance of bottlenecks, often making the areas beyond them inaccessible to newbies. On the other hand NMs following this mechanic (as specified in the OP) would lose their aggressive status when traveling through bottleneck areas to avoid blocking them.

But hey, not at all surprised that you'd be against NM hunting that actually involves fun, active and actually challenging searching, instead of standing in one place wasting time