Blizzard recently stressed that using any mods in Diablo IV is forbidden. All mods, no matter how benign their effects, are treated the same as cheating, and...
Blizzard says that modding Diablo IV can result in a permanent account ban::undefined
I'm not ever participating in those aspects of the game anyway. I'd be far more likely to buy content if they had an offline mode and published new content as DLC.