I find that relatively straightforward to do… when all we want to do is fetch data from a structure stored in a JSON string. But the minute we want to manipulate it, we run hard into the fact that TW’s data is generally either single strings or lists of strings, themselves stored as single strings. We could certainly build tools that simplified doing this, but I believe they would always be going against the grain of TW.
Fair warning: this is an impossible problem to do thoroughly. JSON is not what is called a regular language, and so cannot be reliably parsed with regular expressions. This has to do with the arbitrary deep nesting it allows. You can use regex to parse specific JSON formats, but things fall down as you get more complex. The same is true with HTML, and my all-time favorite StackOverflow answer shows the exasperation of trying to explain that over and over.
Count me among the sceptics. I’m thinking about trying to do something similar to your Tips and commentary - Notes on tiddlers stored in a data tiddler, to demonstrate other ways to create it and document it, but I don’t expect that this will ever be a large part of my TW experience. (I looked at it a little last night, and if I can do it in a few hours over the weekend, I will probably try to write up my results.)