This reminds me of the absolutely brutally fantastic feature of Unreal Engine shading system. A Master-material.
Basically, you create a simplified instance of your shader with any parameters exposed you want. No coding required.
So for example a car shader, you would build the complex network of full shader using regular CoronaMTL (a "Master shader" ), and then create a shader-instance from it that would expose glossiness and color for example. Anytime your would create another color of car shader, you would use your master-instance, which even 3 weeks old monkey would be able to, using just 2 clicks. People could share those.
Of course, another benefit is the propagation from master into instances but that's other topic.
A full OSL support in Corona would do this in more complex way. But master/instance shader is fantastic thing to create as many specialized 'fast-to-use' shaders without having to hard-code dedicated shader for everything (car-paint, skin-shader, sand-shader,etc...).