RDAP has the benefit of being JSON, but even then it’s a reaaally crappy format. For example, contacts are represented by the jCard pseudo-standard, which is a JSON version of vCard, and it’s completely awful and hard to deal with. Basically instead of a nice JSON object, it’s arrays in arrays in arrays…
RDAP should get better in the future versions, but I’m not sure registrars will follow in good faith because the initial specs were a bit of a shit show.