The purpose of this patch was to get undo with RNA information in a quick and dirty way, I looked into the proper way with RNA only after that, so these commits have a dependency, and I won't…
Ok I see your point now, this is assuming that different nodes with the same input name have the same meaning, so the value can be copied from the previous one. This makes sense sometimes, maybe…
I don't think different default values is a bug, it's reasonable for different shaders to have different default values, they shouldn't interfere with each other.
That is only the default "Roughness" value for Principled BSDF. Glossy BSDF also has a "Roughness" of 0.5 https://projects.blender.org/blender/blender/src/commit/b1185da40341bf1fb6deda37449857facc4…
This issue is not limited to the name "Roughness". For example Principled BSDF has a field called "Transmission" with a default value of 0. If I write another shader with a "Transmission" field…
Committed as 6fbc52bdca3b38872c178dbafe0abc92328927e3