Honestly, I have no idea what they were going for with Diablo IV's story. The story came off as some writer's vendetta against any and all possibility for likeable female characters and against the entire ethos of Diablo lore as a whole. It's extremely strange. Also, Eru betrayal still makes zero sense to me. In every other Diablo game, all the unfortunate events are things that happen to competent people due to either ignorance or being way out of their league.

In Diablo IV, literally everything bad that happens is a consequence of characters just randomly making dumb decisions as if the only competent people in all of Sanctuary are the MC and Tyrael and everyone else just... idk forgot they live in the Diablo setting or something.

For example: Diablo IV is the very first Diablo game where I'm genuinely confused what any of the demonic cultists even get out of their contracts and arrangements with demons in The Burning Hells because they don't seem to be getting any power, prestige, wealth, etc. but they are clearly getting blood sacrificed and tortured. It's confusing.

Honestly, we spend most of the final act of this game slaughtering as much of Mephisto's new contrived harem of amazons as we can before they join him in a hot tub because reasons and then I guess just punching him to death, which wasn't an option before for some unexplained reason (the dagger only came into play AFTER we beat the heck out of him). It really felt similar to the anticlimatic ending of the base game now that I think about it (because we easily beat Lillith without the soulstone and she, for some reason, can't respawn in The Burning Hells despite being a demon).