People understand JSON fairly commonly as they can see what is happening in a browser or any other system - what is the equivalent for GRPC if I want to do console.log(json)?

GRPC for most people is a completely black box with unclear error conditions that are not as clear to me at least. For example what happens if I have an old schema and I'm not seeing a field, there's loads of things that can be wrong - old services, old client, even messages not being routed correctly due to networking settings in docker or k8s.

Are you denying there is absolutely tones to learn here and it is trickier to debug and maintain?

I'd go with `cerr << request.DebugString() << '...' << response.DebugString();`, preferably with your favourite logger instead of `stdout`. My browser does the equivalent for me just fine, but that required an extension.

I buy the familiarity argument, but I usually don't see the wire format at all. And maintenance-wise, protobufs seem easier to me. But that's because, e.g., someone set up a presubmit for me that yells at me if my change isn't backwards compatible. That's kind of hard to do if you don't have a formal specification of what goes into your protocol.