You're basically taking away a fine pencil and replacing it with a ink stamp.
not really as the alternative is that your artist sits around getting depressed because nothing looks like it should, but he has got no control of what he's doing. Lighting and texture work involves a lot of subtle tweaking that often requires visual feeback to do well.
leaving it to a coder and trying to explain what something is in words just doesn't work, particularly when you need it tweaked.
Remember in Rifa, we spent days trying to get a specular map, and even with examples rendered with a 3dsmax material you didn't really understand what it was that the texture did.
the core set of tools that an artist is going to use is going to be made up of a series of fairly generic shaders.
Specular maps and masks and possibly fancy bump mapping. having precise control viw WYSIWYG tools means that you can tweak the map and the shader and experiment more with these base effects to get the variety you need.
Coding shaders is often more trial and error and somewhat tedious and in many cases leads to lazy artists not producing work. Particularly if they don't get to tweak at all.
Some shaders obviously don't need so much artist input, but essentualy taking control away from the artist is like trying to finish your work blindfolded and restricts creativity.
Artists should really be in control of visuals and be able to create assets that are designed with a specific look.
With trinity one of the nost frustrating things working on rifa was that the look of the game totaly changed from one day to the next depending on what you felt like tweaking. SO I might have spent several hours compensating for something you did that looked bad and ruined my textures, only to find that the following build was totaly different again and needed to be relit from scratch.
I'm a firm believer that artists and coders should 90% of the time stick to what they do best. Only problem I see if that these extra tools are a hell of a lot of work for one person to produce. But thats why games are created with teams of programmers and artists, rather than a couple of individuals anyway. And those that dabble in both sides usualy have a solid understanding and proficiency in both.