Highly Notorious Monsters

[Atoli]

I used to think time sinks like HNM spawns served no purpose, but it did, it made items a lot more exclusive,[...]

But that's just not very good game design.
If you want certain items to be and STAY really exclusive and valuable, you should do so by making the fight itsself hard, not the way people can try it.
Or by only making materials drop which have to be gathered from different HNMs AND be combined by a high lvl crafter.
There are so many ways to make items exclusive, why use the laziest (for the developer) and most riddiculous (for the player) way?