I mean conversely every second week on HN someone complains about "inefficient modern development practices" and this is the sort of minor thing which would be trotted out as an example.

So I'd argue it's not an unreasonable question (although I lean closer in: better types then JSON is the problem, since a decent text serialization format is always going to be needed for debugging and development).

This sounds like it wants to be a fundamental IPC facility in Linux, which seems like a major thing.

Any binary format can be dumped to a text when viewed for debugging. That’s really a nonissue. Have the tools dump to JSON if you like.