Totally agree. In fact, they even used HTML inside the "text" property so, in fact, they mix JSON with HTML which doesn't seem to make a lot of sense.
You can have a nice structured HTML and it will be as portable, as interoperable (if not more) as that JSON.
Another take on this (by my colleague from CKEditor team): https://medium.com/content-uneditable/a-standard-for-rich-te...