Basically, being able to sculpt on a model without affecting the details of other layers.
This is possible right now by playing around with the visibility of layers.
For example having a skin pore layer, disable this layer and do your sculpting on your base and enable the layer again, the sin pores will be unaffected.
However if the skin pore layer is visible and you sculpt on your base, it will mess up the skin pore details.
If after the fact you decide to disable or remove the skin pore layer, you will find the the skin pore details are now embedded into your base object.
While there are brushes that allow you to sculpt on your base without really affecting your detail layers, allot of sculpt brushes you are not able to use, like flatten, smooth, wax, amplify, bulge, etc.
Leaving you only with the more basic brushes, like the sculpt brush, knife and what not.
So basically having 'additive' layers allows you to have more clarity while making adjustments on sculpts with multiple layers. As you do not need to disable the visibility of your layers to make adjustments to the base.
You could argue against this, as it would not be 'the correct workflow'. As in adding details before you have your base model/sculpt done.
But there are many benefits to this as well. Art direction, blendshapes, posing and adding 'correctives', etc. all without needing to go in 'blind'.
I realize this might not be an easy fix, and it is 'just' a quality of life thing.
But making your tool more artist friendly is always a good thing right? =]
