Is JSON a format that needs improvement for human readability? I think there are much better ways to present data to users, and JSON is a format that should be used to transfer data from system to system.

If you're reaching for a tool like this, it's because you don't have a well-defined schema and corresponding dedicated visualization; you're looking at some arbitrary internal or insufficiently-documented transfer-level data with nested structure, perhaps in the midst of a debug breakpoint, and need a quick and concise visualization without the ability (or time) to add substantial code into the running runtime. Especially if you're working on integration code with third parties, it's common to come across this situation daily.

I think yes? I fairly often find that I have something in JSON, which probably is from some system to system comms, and I'm trying to read it. Once it's not trivially small I often pipe it through jq or python -m json.tool or whatever, I like the idea of something that just does a better job of that.

If you discard the human-readability component of it, JSON is an incredibly inefficient choice of encoding. Other than its ubiquity, you should only be using JSON because it’s both human and machine readable (and being human-readable is mainly valuable for debugging)