Thats why 4 works for me. All these characters we meet and (mostly) care about have horrible things happen to them, we fight back against the corruption and death of humanity, we see the cosmic struggle of the creator of humanity's inability to change her innate evil nature... and nobody cares but us. The fragile, slowly rotting realm of humanity exists for a few more years, perhaps, and the only one who understands or cares about what we went through isn't even human by nature. Not to mention every single side quest basically results in us making things worse for individuals but preventing larger tragedies (potentially).
It offsets the power fantasy of kill crushing demons to death in a way that keeps it fresh versus d2 letting you square up with all the primes or d3 being.... whatever the fuck d3 was. Imagine d3 trying to handle Lorath's death, with exposition dumps and a talk talk talk quest and a monologue about the games themes. D4? Dude gets axed, we avenge him, and Tyrael goes 'we don't have time to grieve right now, help me bury him we have shit to do'. That simple grave hits infinitely harder than dumbass Leah getting got.
Plus d4 gets the fuck out of its own way after the plot resolves and isn't trying to pretend its anything but a glorious loot treadmill now that I'm into torment difficulties.
Yea, it perfectly sums up the setting, which is always bitter victory for man, the cost of which is essentially everything, and the results are temporary, its the quintessential raging against the dying of the light, Lord of Hatred did it particularly well, with the entire last act having you rummage through the OG Horadrim's little rooms, its restated the obvious truth.. Tyrael found these men, got them to band together, and ultimately doomed each and everyone of them to fighting against the Primes (and in Kulle's case, being attacked by his own people for being too ahead of the curve) they couldn't highlight it harder with Tyrael himself handing off the Stones to Kulle, the man who would INVENT A WAY TO BIND PRIME EVILS and his reward is to be stricken from his order, his name stricken from history, and be forever maligned despite being totally correct, same with Jerrad Cain and Tal Rasha, all essentially lead like a pide piper by Tyrael to their doom.. for His people's War, and its still the most just outcome.
all while Tyrael stands beside Lorath, a man who Tyrael shaped the entire life of, and after this moment, would go and die just like all the rest, its very tragic and does a great job at laying out the broader themes of the Diablo setting, none of the settings hero's are really remembered, The Horadrim are treated like myth, Uldyssian was forgotten by everyone except his own brother and Rathma, the D1, D2 Hero's either died horribly after corruption or quietly, as unknowns, the D3 Protag likely was met with a fate similar to Uldyssian, too powerful to live, and the D4 Protag is a nobody, they start a nobody, and end a nobody, despite all you accomplish, no one will know you even did anything, except the human looking, but inhuman acting, Tyrael, who won't even shed a tear for Lorath's death.
Edit*, I believe Lilith acheived the impossible in the very end and changed her nature, and this likely made her no longer a true demon, and probably died forever because of it.
