Why JSON? Just use a simplified subset of HTML and ignore styling+scripts for commandline. And for GUI/Web you can still offer the full HTML+CSS+Scripting-experience.
<section name="Options"><checkbox flag="c" label="Compile" /></section>
It shouldn't be a hassle at all to convert a man page to a UI that speeds up actions and avoids common errors.Anyway, this idea is free, so feel free to take it and do whatever, even full HTML (:
The suggestion was a simplified subset of HTML.