Fog effect and bedrock particles for the deep dark biome

I remember that in MC 1.7.10, that mist appeared after descending in the layers near the bedrock and when we reached this unbreakable stone, some particles appeared indicating that we had already reached the deepest but unfortunately this effect was removed, taking away the "mystery "to those depths.

Now, what if these two effects return for the arrival of the "Deep Dark" biome? I think it would be a good detail and more with the appearance of the Warden it would be even more terrifying; now I think both effects were removed due to a performance issue but knowing that they are working to optimize the new generation of caves and such, why don't these effects come back again?