Demons want the world to burn. Deckard Cain as the Adventurer, and a motley crew of allies want to stop the demons. It's a loot grind along with the clash of swords, talons. Then, the inevitable confrontation with one of the Lord of Hell himself. In Diablo, like most loot-centric action RPGs, story takes a backseat to gameplay. The gameplay is unquestionably great in Diablo 4 Gold.
The gorgeous, illustrated cutscenes are breathtaking, the voice acting is excellent and there are standout set-piece moments and puzzles. However, all of this doesn't change any of the facts that show that the plot overall isn't great. Many players won't care and are simply happy to have the chance to take certain demons back to hell, but the game could be much richer and more interesting with better growth of its lore.
There is a delicate balancing game in any RPG as with each new mechanic introduced the game could be jarring players from its world and making them too aware of the artificiality of the whole. Action RPGs like Diablo Diablo 4 tend to be "just one more run" experience, despite certain aspects of them that jar the player.
The core danger to experience in Diablo 4 is the theme park effect created by the game's MMO elements. Being able to watch a crowd of players run ahead to converse with the same NPC, and buy Diablo 4 Gold then start the same quest to fight the same apocalyptic evil creates the impression one is simply hopping from one place to the nextone, no becoming the hero, but just another park-goer.