Currently I think downloading materials CML materials is too much work - unfortunately!
My biggest reservation on CML is that people are far to anarchistic and sloppy with their naming of shaders and maps - and references to maps - giving one big mess when imported.
Without a convention on exchanging these materials in terms of naming, placement ect - the gain is to little! Ordnung muss sein!!
In my opinion materials should be named first by category - then main subject - then - sub subject - fx. Metal_Chrome_Scratched that helps finding the material. Using Max' own naming like 'Material#12325" should be punished with 10 whip strokes and potential execution by dawn. Thats simply not a way to exchange materials. Maybe a username should be added somewhere to prevent collision with similar materials, - I don't know.
Naming of referenced maps should follow the same naming convention fx. Metal_Chrome_Scratched_Reflection, Metal_Chrome_Scratched_Bump ... ect.
- and should of course be referenced in the material Relative - preferably to a subfolder placed the same place as the max file containing the material - in other words : /Maps/Metal_Chrome_Scratched_Reflection, /Maps/Metal_Chrome_Scratched_Bump.
I don't know if it is really necessary to download a MAX file for getting a material - MAX support an XML way to save material - but I don't know how open it is to support external renderers like Corona - Maybe that should be another feature addon on Ondras list.
I hope I will open some kind of debate on this subject, because I think it is needed to make CML usable. - and actually that goes for other libraries like TurboSquid, DesignConnected ect as well.