Texture painting should be as simple as going to the Texture Paint workspace, and adding a Base Color texture slot.

After testing this though, I think this texture paint overlay has deeper design issue.

In texture paint mode you mainly want to see either the individual texture (with or without lighting), or the textures as part of a full material. Setting the color to Texture in solid mode and the lookdev modes already handle that, so what is the point of having an overlay?

The one problem that I think it solves is that it ensures you always see the texture when entering texture paint mode, regardless of what the shading mode is set to. But then we should simply force the solid mode color to Texture for objects in texture paint mode. And probably add support to combine it with matcaps.

When both the overlay and the shading draw the same texture the results will not look good no matter what we do. So to me it seems we need to leave the texture drawing to the shading, and not have this texture paint overlay at all.

@Brecht Van Lommel (brecht) I don't think we should remove the overlay. The main reason (at the moment) why I think, for painting, that the texture overlay is more useful than the Texture on Solid is that it displays the active texture more accurately.
The Texture on Solid Mode on the other hand is washed out and because of that a worse way of previewing the texture and bad for color picking.

If both the Overlay and the Texture on Solid Mode would look the same in shaded and flat then the differences would be that the Overlay is available in any shading mode and only displays the active texture on the active object. Texture on Solid however displays the active texture on all objects in any object mode, which is also very useful.
Even if they will look the same, they are used differently.
The overlay would mainly be used in any specific object mode while directly working on it (painting weights, textures, vcolors) and the texture on solid would be a helpful preview for modeling, UV work, model/set assembling, etc without directly working on the texture itself.

Also I think the overlay, if removed, would still need to be accessible in Weight Paint Mode and Vertex Paint Mode, at least with the current shading options. Otherwise the settings and accessibility would be a bit inconsistent.

In D3770#86110, @Julien Kaspar (JulienKaspar) wrote:

@Brecht Van Lommel (brecht) I don't think we should remove the overlay. The main reason (at the moment) why I think, for painting, that the texture overlay is more useful than the Texture on Solid is that it displays the active texture more accurately.
The Texture on Solid Mode on the other hand is washed out and because of that a worse way of previewing the texture and bad for color picking.

There is no good reason for Texture on Solid to display the textures washed out I guess, also outside texture paint mode.

If both the Overlay and the Texture on Solid Mode would look the same in shaded and flat then the differences would be that the Overlay is available in any shading mode and only displays the active texture on the active object. Texture on Solid however displays the active texture on all objects in any object mode, which is also very useful.
Even if they will look the same, they are used differently.
The overlay would mainly be used in any specific object mode while directly working on it (painting weights, textures, vcolors) and the texture on solid would be a helpful preview for modeling, UV work, model/set assembling, etc without directly working on the texture itself.

Right, what I meant is that it could show as if Texture on Solid is automatically enabled for the active object only, when in texture paint mode. This is effectively what we did in 2.7x.

Also I think the overlay, if removed, would still need to be accessible in Weight Paint Mode and Vertex Paint Mode, at least with the current shading options. Otherwise the settings and accessibility would be a bit inconsistent.

Weight and vertex paint modes could indeed keep the overlay.

The thing about the washed out texture is about color management. The solid mode is color managed using the diplay profile. But the overlays are not and are simply outputed in sRGB space.

This is a bigger problem than it seems because color picking then should be aware of the display transform.