First off, I simply used some of PCRE for the syntax, as it's what I'm familiar with. \w could be easily replaced, and non-greedy matching is a relatively common extension.
As for when your record spans multiple lines, with recursive structures, the previous regex is for extracting simple atomic data from a json file, which is usally what you want in these cases anyway. If not, the json(1) utility can, I believe, extract arbitrary fields, and composes well with awk, grep, etc.
Yes, the json utility can process a JSON file into key:value pairs. Now ask yourself: if you end up with key:value pairs on stdout, why couldn't that have been the format in the first place? Why artificially impose not one, but two layers of complications (one as JSON, the other as the specialized json tool to process JSON)? Why not just keep it simple and go directly to a flat file ASCII format to begin with?
Well, it means not rolling your own parser. But that's not hard. The real advantage is when you actually ARE dealing with structured data, with nested objects. Most standard UNIX formats are bad at this, and sometimes you find it necessary.
Also, because JSON is so common, you get really good tooling for handling structured data by defult, instead of kinda-okay tooling for 50 different slightly-incompatable formats. 10 operations on 10 datastructures vs 100 operations on 1, and all that.
But for unstructured data, or for one-level key/value data, JSON is overkill. You can use DSV, like this:
