Thanks for the question and tip.
Yes, to be honest, I was thinking about it - but until now there was no real inquiry for JSON.
In contrast, many users use the XML output and other tools also process the XML files (eg. Nagios : https://www.hdsentinel.com/tutorial-hdsentinel-nagios.php ) so I'd surely not say "XML is not used much today anymore"
Please let me know which sections/information would be the most important (for the integration) as then it is possible to focus on that area first (maybe you can send a very short sample to illustrate to info (at) hdsentinel (dot) com)
Then maybe you can also have a tutorial about how to integrate/connect with grafana