The initial pitch barely mentions the part of the game that makes it so ~~much fun~~addicting: You get to beat on pinatas until some loot pops out. Then collect the loot and/or convert it into in-game currency.
Diablo was one of the earliest games to start exercising those little dopamine hits of microjoy when the monsters go pop, hoping for just one more bit of treasure/xp/whatever.
Actually people quickly got bored with item collection with wide availability of duped items and gold(with exception of some variant gameplay groups which played legit), the game actual attraction was its randomness(dungeon layout/content) and challenge to complete levels at higher difficulties.
Items and gold were central to Diablo2, which is exactly the "pinata simulator" you describe.
In general, Diablo could be completed with trash items or(with sorcerer, even nothing worn).
Diablo was one of the earliest games to start exercising those little dopamine hits of microjoy when the monsters go pop, hoping for just one more bit of treasure/xp/whatever.