I noticed for a while that there is some lost functionality from 2.7x when switching to Sculpt Mode in terms of the mesh that is displayed.
- Most modifers have no visible effect in Sculpt Mode.
- When modifers are enabled, shape key sculpting is not showing any changes anymore.
- When entering sculpt mode the material in the first material slot is set for the entire mesh.
- The wireframes are always tessellated.
- UVs and texture previews don't work anymore.
These were incredibly useful when using Sculpt Mode for workflows like retopology, shapekey modeling, mesh adjustments based on texture previews, etc.
I'm not very familiar with the technical process and reasoning in the background but as far as I know there are 2 versions of the mesh for the 3D viewport.
When sculpting in Eevee and with Wireframes Overlay turned on this becomes very visible.
The wireframes show the tesselated sculpt mode mesh and the rendered mesh is the one that is used otherwise (with UVs, Materials, Modifiers, etc.)
This is likely no easy thing to fix but perhaps we can start a discussion on how to possibly fix this over here.
Perhaps there can be an option to switch the preview mesh while sculpting.
I assume that the biggest reason for there to be 2 types of mesh preview is performance?
Since there are also options like "Fast Navigate" that change the way the mesh is previewed for performance reasons and also older options like "Show Diffuse Color", perhaps there can be an option like "Simplified Mesh Preview" or "Show only Mesh" or some better named checkmark option in the options popover in the Sculpt Mode Top Bar.
This option can be enabled by default but if disabled it would switch the preview mesh so that all the above points can work again.