I don't think it's so much the aspect of the grind itself as much as it's like...
The grind feels so rewardless

Day one I had the challenge log to do which was not terribly painful and saw a couple NM spawns to break up the nothingness

but then day two once that was gone... It was like spending 1.5-2 hour periods in there just killing mobs. Not seeing any NM's, no challenge logs to watch and complete, no loot dropping to go open up, no quests to follow and see. Just sitting in a little white patch killing the same thing over and over while the "NM train" was nearby fruitlessly trying to spawn a boss. Then when It's time to do something else, All i see is less than 10% of a single level and nothing else

It just feels bad doing it and leaves me feeling bad afterwards for doing it