I think there are benefits of interpreters as well as compilers, possibly for the same programming language in some cases (although some programming languages are better for use with interpreter and some are better for use with compilers).
I think JSON is not the best format for the persistence though (despite their claim that it is better than binary formats, it has many problems); it has many problems, such as not a proper integer type and not non-Unicode text types or binary types, etc; and different format would better, such as DER. If you use DER, then you can use better types, better character sets, binary data, and not limits to how big numbers can be, etc. (JSON might work for JavaScript, but even then only for some types; JavaScript has more types than JSON has, including JavaScript does actually have a integer type even though JSON does not.) (With using JSON, it will just mean that you will then have to wrap other data in JSON anyways (e.g. encoding DER as base64) and the meaning will have to be converted.) (Also, you can work around not being a text format, because you can have a program to display them, like a program can be used to display any other kind of data in other ways (e.g. syntax highlighting, pictures, auto formatting, etc).)
I think JSON is not the best format for the persistence though (despite their claim that it is better than binary formats, it has many problems); it has many problems, such as not a proper integer type and not non-Unicode text types or binary types, etc; and different format would better, such as DER. If you use DER, then you can use better types, better character sets, binary data, and not limits to how big numbers can be, etc. (JSON might work for JavaScript, but even then only for some types; JavaScript has more types than JSON has, including JavaScript does actually have a integer type even though JSON does not.) (With using JSON, it will just mean that you will then have to wrap other data in JSON anyways (e.g. encoding DER as base64) and the meaning will have to be converted.) (Also, you can work around not being a text format, because you can have a program to display them, like a program can be used to display any other kind of data in other ways (e.g. syntax highlighting, pictures, auto formatting, etc).)