Divine being listened to 'leaked' audio, and noticed Blizzard haven't renounced of their wicked ways regarding voice-effects (too much, crossing taste borderline tastelessness and growing into borderline stupidity), therefore - D2X2! With bad bad storytelling, with appeal to none (over 12).
Divine observation: *some* parts of the storyline, namely enchantress, Zoltan Kulle and Shen weren't bad - almost (and likely) as if there were *one* competent writer in a team, who wrote these, radically different from plebeian scum who wrote most ('i'm afraid of the spiders, boohoo, and horny and not funny at all' - probably a game representation of a person who wrote his lines, except the muscles, of course). Learning that, possibly good, Shen-quest is a just a sidequest to the whole fallen-angel stupidity (sic!), The God has no faith at all at Blizzard capability to have any decent Diablo franchise based lore. Ever. It is beyond redemption. With their "nephelem", spelled wrongly and resembling to angelic rape and/or interspecies breeding, both equally disgusting to heavenly being, and also disgusting in their 'supremacy' over... everything - the protagonists in Diablo franchise were unknown heroes, normal men (despite later 'kingly born' nonsense), not supernatural beings, and D3 is an exception to this rule, and not in the good sense, The God declares.
Having substantial knowledge on this topic - heavenly, one must say, I, Tiberius Claudius Caesar Augustus Germanicus, The God, declare following:
There are two basic versions of writing a lore, as a literary background of book, film or a game.
Blizzard was foolish enough, perhaps in overconfidence, or sheer lack of knowledge and experience, to switch from one to another.
1. No-lore or lore revealed on a need-to-know basis
Events happen, sometimes following some basic order, sometimes even chaotically. Not much is known of true background and that what is, usually revealed later in progress, perhaps by a storyteller or story character generator. This approach requires less effort and less chance of mistakes, inconsistencies or (even) stupidity. Search no longer, the examples are first two games in the franchise - player basically knew little of grand scheme of things.
In D1 (memory may falter on this), the player was nameless hero, fighting all-corrupting evil buried at depths, who seeks to release itself. The true nature of evil was unknown (except that it was up to no good, but no 'world domination' concept yet), and the goal was saving Tristram and town inhabitants of it, by defeating followers and then evil itself. There is little indication that all what happens is part of something bigger, let alone abundant lore as such, making in none the tiniest bit less vivid or dark or atmospheric.
In D2, the player knows a bit more about the ways of the world, chiefly by (excellent!) decision that old D1 hero loses his battle with consuming evil, and becomes a vessel of it. Still, Andariel, Dureil, The Countess and many others are just names and random evils - Deckard Cain, the chief storyteller of the game fails to mention (stupid) fact about first two - as the player knows, there are three Prime Evils (which he destroys) which came to Earth to conquer the human race, and that there is Heavens, represented (but not quite!) by story generator Tyriel. Heaven is largely uninterested on human affairs, to the point of ignoring. Facts which are stupid by nature, as that non-speaking Duriel is ranked Lesser evil, and weakly described Hell intrigues are (by good choice!) skipped entirely, or never even intended to be as such - why Duriel is not a just powerful beast left to slow possible pursuers down? Soulstones are mean to destroy demons and to achieve victory.
1. Vast and consuming detailed lore
The Morrowind/Elder Scrolls class. The Warhammer class. The White Wolf class. Those are gaming examples, first being computer based only, others more of an RPG background (which The God doesn't play godself, but knows it well). Lore is vast and well thought-out, as well skillfully written, with little to none inconsistencies, often shared with players when (and if) he wants it - of thousands of written Morrowind pages of text, the player could skip almost all - but one immersed in a good story and interested by it could find out much more - but not all! - mysteries and open-ends are ever-important!
The Hobbit/Lord of The Rings/Silmarilion lore - mentioned here as one very well-known, and also for their gradation. Lore is clearly unfinished or nonexistent in The Hobbit (might actually have more in common with films than most people think, but also not, and this is not the place or time to discuss it) - there are inconsistencies with later works, but Tolkien, as a master of creating worlds, doesn't needlessly babble of everything that falls on his mind at the moment. That allows Lord of the Rings to deal with amazingly few changes, and continue a finished story seamlessly. Lore is much, much broader here, but (as said before) leaves lots of open ends and unexplained things. The reader is immersed in the story so. The reader seeks more. Therefore, Silmarilion, the unfinished - but the book of this type is always unfinished. The God giveth this example, because it took Tolkien the rest of his life to write both Lord of the Rings and Silmarilion, a fascinatingly detailed work that actually *explains* motives and happenings from the lore/past.
Warhammer and White Wolf stuff are written by 10,000 monkeys with a similar number of typewriters, but edited heavily throughout the years - resulting in well thought-out gaming worlds *with* endless possible happenings and scenarios. The God would add that Blizzard is *borrowing* heavily from Warhammer lore in WC/SC/WoW - not enough, one might say, Pandas be damned!
Where D3 stands from a lore perspective?
It tries to be in the second group, but fails miserably - story is weak and flawed with inconsistencies - despite various 'loremaster' yesmen which Blizzard PR promoted as a 'names' and 'masters of the craft' (sic!) - The God sees them as trash, writing nonsenses for cash, with no interest in it, or any talent whatsoever.
WC/SC/WoW does far better job in not bombarding players with their respective good sides and flaws continuously, while D3 does - divine being is, for example, *quite* uninterested whatever in the world happens with scoundrel - in Eternal City, The God sentenced this kind to punishments of justly chosen measure, and never listened to their 'lore' - plebeian scum could tell it in the dungeons as much as they like, and as much as guards allowed, but not to divine ears - and so should be in D3 - heavenly being refers to 'mute completely' option, or in more open game, The God would opt gladly to kill the petty criminal on sight, regarding of his past. The God would opt to kill Templar too, when he starts to bore divine being. This ability would represent a nice open-endness and an element of choice. But D3 is one of least open games known to divine being, while it shouldn't be so - even a possibility of making a wrong turn somewhere is taken away [The God again ponders how this was possible, if any replayability was in mind. Heavenly being finds no answer to this.]
So lorewise, D3 tries to be something that it is not - a lovingly crafted world with matching lore. Comparing it with ones mentioned above puts it down to the depths of bad fan-fiction. A bad decision which could have been prevented by 'hinted lore' mechanism, and a (far) better storytelling.
How does this belong to villain thread?
The God declares that, despite truth is (supposedly) revealed by a sound sequence, it is going to be downright stupid. Endless recycling of Diablo as villain and killing it in each game resembles on recycling Tong Po in Kickboxer, time after time. Or, better yet, Freddy in Space. If Diablo is going to be nemesis in a franchise, he should be a generator of story, not the antagonist itself. Or, we are destined to repeat 'but Michael wasn't *really* dead, once again' forever.
Diablo universe is badly made dark-fantasy world, and it wasn't so in the beginning. But the number of badly written books or trilogies (sic!), trying to create *something* took its toll. Only unconnected ends are future ones, and it can still function, but this crippled possibilities considerably. Instead of the vivid world steaming with life, both past and present, we got mind numbing sequence of 'fight same archvillain in a short amount of time.
Many games, facing similar problems, decided to go in the future or past, changing scenery and/or protagonists/antagonists. Diablo only (without reason) changed character classes. The next game in the franchise has to embrace change, or have recycled Diablo again. With butterfly queens, chosen ones in form of nephelem and princesses to save. And Pandas, definitely, as a playable race, in so far purely human settings. Wasted potential.
Regarding gothic feel - The God tried a divine hand on PTR - if *all* sounds are muted and cinematics skipped, the world is dark and brooding. Meaning that stupid storytelling and papercut characters spoil the feeling, instead contributing to it. Also, 'more diverse' elites tend to cast 'puddle of no-seeing' spell - half the screen flashes in different colours - there is acid, poison, ice, fire, lava... some created by The God godself, most by enemies. Oh some of them flash, too. The character is hard to find on screen, non-flashing projectiles too - resulting in the game to be anti-micro oriented. 'Puddles' are great evil, forcing players to play 'Blizzards way', which is maybe acceptable by some, but not the divine being.