While I love the idea of a super easy, quick and intuitive material system, there is a finite time to code such a thing. I would be more than happy with the ability to hack together something based on the tools that sketchup does allow.
Since enscape is pulling material and texture data directly from the sketchup scene, we could embed multiple sub-materials containing the maps we are looking to use, such as brick, brick-bump, brick-normal, brick-displacement, brick-reflection, brick-glossiness, each as a separate material. If Enscape finds one of the sub-materials provided, it would use these to add these additional parameters to the master material it builds. Would probably be best to choose a very unique identifier for the naming structure.
A sub-material's name can also indicate the strength of whatever map or parameter we are supplying. For example, the name"brick-bump-25"would mean 25% strength bump. If we want to supply only a value, we create a material with a name such as "brick-reflection-25", or "brick-glossiness-33"
The other cool thing about breaking it down like this is it could theoretically give Sketchup/Enscape the ability to do separate scaling for each texture . Not sure if Enscape can handled this info, but this method would provide it. For example, "brick-glossiness-33" material could have a texture with a size of 10' x 10', whereas the main "brick" material texture might be sized at 5'x5'. There are many times when the ability to add a different sized submap can help to disguise tiling.