There is no plan for that. We plan to keep energy conservation for regular material. And diffuse is encoded into as few bits as possible for efficiency so it would not allow a large value range.
Toon shader is different in that regard indeed, as of today and might change, considering the diffuse ramp that do not have any clamped color.
alright, it would be REALLY helpful to be able to boost the diffuse lighting on the toon BSDF for certain important objects/characters in stylized games that have a lot of dark areas
(post deleted by author)
@SebHillaire Hello there 
Since Substrate now uses F0 and F90 for the reflectance, i had to convert my own material function for the Complex IOR (for metals via their IOR n and k values). I was made aware by other commenters on a Youtube tutorial about Substrate, that there is already a “Substrate-IOR-To-F0” node, for those, who want use IOR values.
My question would be, could you also include such a function for the “Complex IOR”, for metals? I attached my material functions code as a text file, if you want take a look at it.
MF_SubstrateComplexIOR.txt (203.3 KB)
@Suthriel Hello!
And thanks for the great suggestion! + an implementation
I have added a TODO for us to consider and review this to be added.
Hello! In our mainline, we added a “Substrate IOR-to-F0 (Conductor)” material function(counter part of the dieletric version “Substrate IOR-to-F0”). The sRGB to linear has been left out, but you can use the sRGBToLinear node if you want to have it. This will be available in 5.8.
Thank you for your suggestion!
/Charles.
@Charles That sounds awesome And i included that sRGB2Linear, because without it, the colors looked way off, way to bright. I first thought, that i needed the other node (Linear2sRGB), but somehow, that formula required the sRGB2Linear to look correct.
Here is a comparsion, left the same materials from the previous post, right its the same, but the sRGB2Linear is inactive. Looks wrong, too bright ^.^ Maybe you just add a note or description, that it might need the sRGB2Linear node to look right in some setups Oh, and we would need 3 sRGB2Linear nodes, since the nodes themselfes are just scalar, not vectors, so one node for each color would be required.
