I must emphasise that the JSON file was developed specifically to handle the large number of files needed in the PBR examples. There is no intent to add this format as a VTK standard.
The examples enhance and build on what VTK offers, it is their role to showcase VTK and provide examples/insipration for users. It is my hope that users don´t feel constrained by the examples, they should take the code and enhance it for their own purposes.
I considered other formats e.g TOML. Whilst mostly supported by CLI11 “tomllib” is new in Python 3.11. At least JSON is supported in VTK and Python and Java. feel free to create your own version using TOML if it is more convenient.