Thanks for the suggestions.
In a future version we will definitely add Roughness Function to the Reflective Shader and Glass Shader, and Ray traced reflections in the Default Shader. Probably for TG4.
Some of the exclusions in each shader are deliberate attempts to simplify the shaders so they aren't too daunting at first glance, and different choices were made according to how I anticipated each shader would normally be used. It would help if the image and function links didn't take up so much space in the window. If we can clean up the interface we could add most of these functions, and have more consistency between shaders. There are some I probably won't add though. Controlling the highlight intensity independently of the reflectivity is not physically correct, so I prefer not to make it easy to do that. When the interface is already busy, that's the first thing I want to exclude. But sometimes you really need to control its overall intensity, so there is a single slider for that.
The Default Shader is the only shader where you can attach images directly (without a separate Image Map Shader) because it's focused on texturing UV-mapped objects imported from other apps. But I know this would be useful on many other shaders. We really need a better UI for this purpose to avoid overcrowding other shaders.
Matt
