Hey, one of the co-maintainers of the project here. And the one that decided to use json.
I agree with you. there are other options for configuration that are much better than json (yaml, toml).
Main reason for chosing json was simplicity. This was my first project in go and I didn't want to spend much time in it either. I found an example that was using json and I saw that I didn't need any external library to decode it. I thought that was good enough, at least for now.
Will probably look into using a library that supports yaml/toml for configuration in the future.
