Without a good material pipeline a shader based engine is pretty much useless.
However you must admit that as of today in most cases standard maps (diffuse, dot3, specular) plus common shader effect (heat, fast fresnel) are enough and it's what the gaming industry currently uses. Make a diffuse map, add/bake to it an ambient occlusion map, add a DOT3 and a specular map and you are done. Then apply in realtime if needed fast fresnel, sub surface scattering, or everything else the developer wants to put in. It's the fastest route if you outsource graphics.
I for one would be very glad to be able to use material pipelines such the one you mentioned, darktree or the new node editor of Lightwave 9, but there is still road ahead in the light of standardization. However there are already shader authoring tools available (starting from the free FX Composer from nVidia) which are very helpful if you use the baked maps approach. Even if the Unreal Engine has its own node editor, you still have to adapt your current art pipeline to work with it, and not everyone has the time anyway to work on custom shaders.
EDIT: Also, Unreal's approach can be mimicked by using an external node graph shader authoring tool.
EDIT2: I forgot to mention Mental Mill, the artist edition being included into FX composer and which should be exactly what I was talking about.