Yeah, I don't really understand the hate for D3's art. It's not the art that really kills the atmosphere compared to D1, it's the gameplay.
In D1 you move slowly, everything is dangerous (especially large groups of enemies), resources are limited, dying has severe penalties, and even shrines can have permanent consequences. Shit is tense and scary.
But in D3 you're a demigod, the entire game is designed toward enabling you to plow through hordes of enemies with maximum efficiency, and unless you're playing on hardcore there are no major consequences to anything. It can be challenging, but due to the way the difficulty selection works, it's only hard if you choose for it to be, and the challenge is more action-y, less survival horror-y.
D2 is somewhere in between