Players who don't reach endgame shouldn't be complaining about endgame content. If it doesn't seem fun to you, fine. That's cool.
But let's actually endevour to be honest. Let's try this honesty thing.
If instead of the harder modes... they called them 'New Game+', 'NG++', etc, and had character advancement and ratcheting difficulty of encounters, with ever increasing progression of loot, you'd be all upons that like you are with any RPG with NG+ modes.
Oh wait, Diablo has that. It has NG+, NG++, and NG+++. What's the difference between this and, say, Chrono Trigger? Oh yes, ratcheting difficulties.
Some people simply don't want to stop using overpowered abilities against overpowered monsters. Some people don't want to constrain themselves to the singular playthrough and some actually enjoy trying to put together a build that allows them to attack the highest difficulties the most efficiently.
This thread comes across as a bunch of 'Stop Having Fun Guys' who don't seem to realize a lot of people really enjoy that, and those people are the ones that give the game longevity, and by longevity I mean 'Is still a cash cow a decade down the road.'
Like Diablo 2.